PostgreSQL 原始碼解讀(14)- Insert語句(如何構造PlannedStmt)

husthxd發表於2018-08-10

本文簡單介紹了PG插入資料部分的原始碼,主要內容包括如何構造PlannedStmt資料結構的實現邏輯,以及其他相關的資料結構,構造PlannedStmt的主函式standard_planner位於planner.c檔案中。
Planned中文直譯意思是“已被規劃過的”,PlannedStmt意思是已被規劃過的Statement(SQL語句),這個資料結構中的元素以及該資料結構的構造是理解後續執行SQL語句的關鍵。

一、原始碼解讀

standard_planner函式,生成PlannedStmt,其中最重要的資訊是可用於後續執行SQL語句的planTree.

 PlannedStmt *
 standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 {
     PlannedStmt *result;//返回結果
     PlannerGlobal *glob;//全域性的Plan資訊-Global information for planning/optimization
     double      tuple_fraction;//
     PlannerInfo *root;//每個Query的Plan資訊-Per-query information for planning/optimization
     RelOptInfo *final_rel;//Plan中的每個Relation資訊-Per-relation information for planning/optimization
     Path       *best_path;//最優路徑
     Plan       *top_plan;//最上層的Plan
     ListCell   *lp,//臨時變數
                *lr;
 
     /*
      * Set up global state for this planner invocation.  This data is needed
      * across all levels of sub-Query that might exist in the given command,
      * so we keep it in a separate struct that's linked to by each per-Query
      * PlannerInfo.
      */
     glob = makeNode(PlannerGlobal);//構建PlannerGlobal
   //初始化引數
     glob->boundParams = boundParams;
     glob->subplans = NIL;
     glob->subroots = NIL;
     glob->rewindPlanIDs = NULL;
     glob->finalrtable = NIL;
     glob->finalrowmarks = NIL;
     glob->resultRelations = NIL;
     glob->nonleafResultRelations = NIL;
     glob->rootResultRelations = NIL;
     glob->relationOids = NIL;
     glob->invalItems = NIL;
     glob->paramExecTypes = NIL;
     glob->lastPHId = 0;
     glob->lastRowMarkId = 0;
     glob->lastPlanNodeId = 0;
     glob->transientPlan = false;
     glob->dependsOnRole = false;
 
     /*
      * Assess whether it's feasible to use parallel mode for this query. We
      * can't do this in a standalone backend, or if the command will try to
      * modify any data, or if this is a cursor operation, or if GUCs are set
      * to values that don't permit parallelism, or if parallel-unsafe
      * functions are present in the query tree.
      *
      * (Note that we do allow CREATE TABLE AS, SELECT INTO, and CREATE
      * MATERIALIZED VIEW to use parallel plans, but this is safe only because
      * the command is writing into a completely new table which workers won't
      * be able to see.  If the workers could see the table, the fact that
      * group locking would cause them to ignore the leader's heavyweight
      * relation extension lock and GIN page locks would make this unsafe.
      * We'll have to fix that somehow if we want to allow parallel inserts in
      * general; updates and deletes have additional problems especially around
      * combo CIDs.)
      *
      * For now, we don't try to use parallel mode if we're running inside a
      * parallel worker.  We might eventually be able to relax this
      * restriction, but for now it seems best not to have parallel workers
      * trying to create their own parallel workers.
      *
      * We can't use parallelism in serializable mode because the predicate
      * locking code is not parallel-aware.  It's not catastrophic if someone
      * tries to run a parallel plan in serializable mode; it just won't get
      * any workers and will run serially.  But it seems like a good heuristic
      * to assume that the same serialization level will be in effect at plan
      * time and execution time, so don't generate a parallel plan if we're in
      * serializable mode.
      */
     if ((cursorOptions & CURSOR_OPT_PARALLEL_OK) != 0 &&
         IsUnderPostmaster &&
         parse->commandType == CMD_SELECT &&
         !parse->hasModifyingCTE &&
         max_parallel_workers_per_gather > 0 &&
         !IsParallelWorker() &&
         !IsolationIsSerializable())//並行模式的判斷
     {
         /* all the cheap tests pass, so scan the query tree */
         glob->maxParallelHazard = max_parallel_hazard(parse);
         glob->parallelModeOK = (glob->maxParallelHazard != PROPARALLEL_UNSAFE);
     }
     else
     {
         /* skip the query tree scan, just assume it's unsafe */
         glob->maxParallelHazard = PROPARALLEL_UNSAFE;
         glob->parallelModeOK = false;
     }
 
     /*
      * glob->parallelModeNeeded is normally set to false here and changed to
      * true during plan creation if a Gather or Gather Merge plan is actually
      * created (cf. create_gather_plan, create_gather_merge_plan).
      *
      * However, if force_parallel_mode = on or force_parallel_mode = regress,
      * then we impose parallel mode whenever it's safe to do so, even if the
      * final plan doesn't use parallelism.  It's not safe to do so if the
      * query contains anything parallel-unsafe; parallelModeOK will be false
      * in that case.  Note that parallelModeOK can't change after this point.
      * Otherwise, everything in the query is either parallel-safe or
      * parallel-restricted, and in either case it should be OK to impose
      * parallel-mode restrictions.  If that ends up breaking something, then
      * either some function the user included in the query is incorrectly
      * labelled as parallel-safe or parallel-restricted when in reality it's
      * parallel-unsafe, or else the query planner itself has a bug.
      */
     glob->parallelModeNeeded = glob->parallelModeOK &&
         (force_parallel_mode != FORCE_PARALLEL_OFF);
 
     /* Determine what fraction of the plan is likely to be scanned */
     if (cursorOptions & CURSOR_OPT_FAST_PLAN)
     {
         /*
          * We have no real idea how many tuples the user will ultimately FETCH
          * from a cursor, but it is often the case that he doesn't want 'em
          * all, or would prefer a fast-start plan anyway so that he can
          * process some of the tuples sooner.  Use a GUC parameter to decide
          * what fraction to optimize for.
          */
         tuple_fraction = cursor_tuple_fraction;//使用GUC 引數
 
         /*
          * We document cursor_tuple_fraction as simply being a fraction, which
          * means the edge cases 0 and 1 have to be treated specially here.  We
          * convert 1 to 0 ("all the tuples") and 0 to a very small fraction.
          */
         if (tuple_fraction >= 1.0)
             tuple_fraction = 0.0;
         else if (tuple_fraction <= 0.0)
             tuple_fraction = 1e-10;
     }
     else
     {
         /* Default assumption is we need all the tuples */
         tuple_fraction = 0.0;
     }
 
     /* primary planning entry point (may recurse for subqueries) */
     root = subquery_planner(glob, parse, NULL,
                             false, tuple_fraction);//獲取PlannerInfo根節點
 
     /* Select best Path and turn it into a Plan */
     final_rel = fetch_upper_rel(root, UPPERREL_FINAL, NULL);//獲取頂層的RelOptInfo
     best_path = get_cheapest_fractional_path(final_rel, tuple_fraction);//選擇最佳路徑
 
     top_plan = create_plan(root, best_path);//生成執行計劃
 
     /*
      * If creating a plan for a scrollable cursor, make sure it can run
      * backwards on demand.  Add a Material node at the top at need.
      */
     if (cursorOptions & CURSOR_OPT_SCROLL)
     {
         if (!ExecSupportsBackwardScan(top_plan))
             top_plan = materialize_finished_plan(top_plan);
     }
 
     /*
      * Optionally add a Gather node for testing purposes, provided this is
      * actually a safe thing to do.
      */
     if (force_parallel_mode != FORCE_PARALLEL_OFF && top_plan->parallel_safe)
     {
         Gather     *gather = makeNode(Gather);
 
         /*
          * If there are any initPlans attached to the formerly-top plan node,
          * move them up to the Gather node; same as we do for Material node in
          * materialize_finished_plan.
          */
         gather->plan.initPlan = top_plan->initPlan;
         top_plan->initPlan = NIL;
 
         gather->plan.targetlist = top_plan->targetlist;
         gather->plan.qual = NIL;
         gather->plan.lefttree = top_plan;
         gather->plan.righttree = NULL;
         gather->num_workers = 1;
         gather->single_copy = true;
         gather->invisible = (force_parallel_mode == FORCE_PARALLEL_REGRESS);
 
         /*
          * Since this Gather has no parallel-aware descendants to signal to,
          * we don't need a rescan Param.
          */
         gather->rescan_param = -1;
 
         /*
          * Ideally we'd use cost_gather here, but setting up dummy path data
          * to satisfy it doesn't seem much cleaner than knowing what it does.
          */
         gather->plan.startup_cost = top_plan->startup_cost +
             parallel_setup_cost;
         gather->plan.total_cost = top_plan->total_cost +
             parallel_setup_cost + parallel_tuple_cost * top_plan->plan_rows;
         gather->plan.plan_rows = top_plan->plan_rows;
         gather->plan.plan_width = top_plan->plan_width;
         gather->plan.parallel_aware = false;
         gather->plan.parallel_safe = false;
 
         /* use parallel mode for parallel plans. */
         root->glob->parallelModeNeeded = true;
 
         top_plan = &gather->plan;
     }
 
     /*
      * If any Params were generated, run through the plan tree and compute
      * each plan node's extParam/allParam sets.  Ideally we'd merge this into
      * set_plan_references' tree traversal, but for now it has to be separate
      * because we need to visit subplans before not after main plan.
      */
     if (glob->paramExecTypes != NIL)
     {
         Assert(list_length(glob->subplans) == list_length(glob->subroots));
         forboth(lp, glob->subplans, lr, glob->subroots)
         {
             Plan       *subplan = (Plan *) lfirst(lp);
             PlannerInfo *subroot = lfirst_node(PlannerInfo, lr);
 
             SS_finalize_plan(subroot, subplan);
         }
         SS_finalize_plan(root, top_plan);
     }
 
     /* final cleanup of the plan */
     Assert(glob->finalrtable == NIL);
     Assert(glob->finalrowmarks == NIL);
     Assert(glob->resultRelations == NIL);
     Assert(glob->nonleafResultRelations == NIL);
     Assert(glob->rootResultRelations == NIL);
     top_plan = set_plan_references(root, top_plan);
     /* ... and the subplans (both regular subplans and initplans) */
     Assert(list_length(glob->subplans) == list_length(glob->subroots));
     forboth(lp, glob->subplans, lr, glob->subroots)
     {
         Plan       *subplan = (Plan *) lfirst(lp);
         PlannerInfo *subroot = lfirst_node(PlannerInfo, lr);
 
         lfirst(lp) = set_plan_references(subroot, subplan);
     }
 
     /* build the PlannedStmt result */
     result = makeNode(PlannedStmt);
 
     result->commandType = parse->commandType;//命令型別
     result->queryId = parse->queryId;
     result->hasReturning = (parse->returningList != NIL);
     result->hasModifyingCTE = parse->hasModifyingCTE;
     result->canSetTag = parse->canSetTag;
     result->transientPlan = glob->transientPlan;
     result->dependsOnRole = glob->dependsOnRole;
     result->parallelModeNeeded = glob->parallelModeNeeded;
     result->planTree = top_plan;//執行計劃(這是後續執行SQL使用到的最重要的地方)
     result->rtable = glob->finalrtable;
     result->resultRelations = glob->resultRelations;
     result->nonleafResultRelations = glob->nonleafResultRelations;
     result->rootResultRelations = glob->rootResultRelations;
     result->subplans = glob->subplans;
     result->rewindPlanIDs = glob->rewindPlanIDs;
     result->rowMarks = glob->finalrowmarks;
     result->relationOids = glob->relationOids;
     result->invalItems = glob->invalItems;
     result->paramExecTypes = glob->paramExecTypes;
     /* utilityStmt should be null, but we might as well copy it */
     result->utilityStmt = parse->utilityStmt;
     result->stmt_location = parse->stmt_location;
     result->stmt_len = parse->stmt_len;
 
     result->jitFlags = PGJIT_NONE;
     if (jit_enabled && jit_above_cost >= 0 &&
         top_plan->total_cost > jit_above_cost)
     {
         result->jitFlags |= PGJIT_PERFORM;
 
         /*
          * Decide how much effort should be put into generating better code.
          */
         if (jit_optimize_above_cost >= 0 &&
             top_plan->total_cost > jit_optimize_above_cost)
             result->jitFlags |= PGJIT_OPT3;
         if (jit_inline_above_cost >= 0 &&
             top_plan->total_cost > jit_inline_above_cost)
             result->jitFlags |= PGJIT_INLINE;
 
         /*
          * Decide which operations should be JITed.
          */
         if (jit_expressions)
             result->jitFlags |= PGJIT_EXPR;
         if (jit_tuple_deforming)
             result->jitFlags |= PGJIT_DEFORM;
     }
 
     return result;
 }
 

二、基礎資訊

standard_planner函式使用的資料結構、宏定義以及依賴的函式等。
資料結構/宏定義
1、PlannerGlobal

/*----------
  * PlannerGlobal
  *      Global information for planning/optimization
  *
  * PlannerGlobal holds state for an entire planner invocation; this state
  * is shared across all levels of sub-Queries that exist in the command being
  * planned.
  *----------
  */
 typedef struct PlannerGlobal
 {
   NodeTag     type;
   ParamListInfo boundParams;  /* Param values provided to planner() */
   List       *subplans;       /* Plans for SubPlan nodes */
   List       *subroots;       /* PlannerInfos for SubPlan nodes */
   Bitmapset  *rewindPlanIDs;  /* indices of subplans that require REWIND */
   List       *finalrtable;    /* "flat" rangetable for executor */
   List       *finalrowmarks;  /* "flat" list of PlanRowMarks */
   List       *resultRelations;    /* "flat" list of integer RT indexes */
   List       *nonleafResultRelations; /* "flat" list of integer RT indexes */
   List       *rootResultRelations;    /* "flat" list of integer RT indexes */
   List       *relationOids;   /* OIDs of relations the plan depends on */
   List       *invalItems;     /* other dependencies, as PlanInvalItems */
   List       *paramExecTypes; /* type OIDs for PARAM_EXEC Params */
   Index       lastPHId;       /* highest PlaceHolderVar ID assigned */
   Index       lastRowMarkId;  /* highest PlanRowMark ID assigned */
   int         lastPlanNodeId; /* highest plan node ID assigned */
   bool        transientPlan;  /* redo plan when TransactionXmin changes? */
   bool        dependsOnRole;  /* is plan specific to current role? */
   bool        parallelModeOK; /* parallel mode potentially OK? */
   bool        parallelModeNeeded; /* parallel mode actually required? */
   char        maxParallelHazard;  /* worst PROPARALLEL hazard level */
 } PlannerGlobal;
 

2、PlannerInfo

 /*----------
  * PlannerInfo
  *      Per-query information for planning/optimization
  *
  * This struct is conventionally called "root" in all the planner routines.
  * It holds links to all of the planner's working state, in addition to the
  * original Query.  Note that at present the planner extensively modifies
  * the passed-in Query data structure; someday that should stop.
  *----------
  */
 struct AppendRelInfo;
 
 typedef struct PlannerInfo
 {
     NodeTag     type;
 
     Query      *parse;          /* the Query being planned */
 
     PlannerGlobal *glob;        /* global info for current planner run */
 
     Index       query_level;    /* 1 at the outermost Query */
 
     struct PlannerInfo *parent_root;    /* NULL at outermost Query */
 
     /*
      * plan_params contains the expressions that this query level needs to
      * make available to a lower query level that is currently being planned.
      * outer_params contains the paramIds of PARAM_EXEC Params that outer
      * query levels will make available to this query level.
      */
     List       *plan_params;    /* list of PlannerParamItems, see below */
     Bitmapset  *outer_params;
 
     /*
      * simple_rel_array holds pointers to "base rels" and "other rels" (see
      * comments for RelOptInfo for more info).  It is indexed by rangetable
      * index (so entry 0 is always wasted).  Entries can be NULL when an RTE
      * does not correspond to a base relation, such as a join RTE or an
      * unreferenced view RTE; or if the RelOptInfo hasn't been made yet.
      */
     struct RelOptInfo **simple_rel_array;   /* All 1-rel RelOptInfos */
     int         simple_rel_array_size;  /* allocated size of array */
 
     /*
      * simple_rte_array is the same length as simple_rel_array and holds
      * pointers to the associated rangetable entries.  This lets us avoid
      * rt_fetch(), which can be a bit slow once large inheritance sets have
      * been expanded.
      */
     RangeTblEntry **simple_rte_array;   /* rangetable as an array */
 
     /*
      * append_rel_array is the same length as the above arrays, and holds
      * pointers to the corresponding AppendRelInfo entry indexed by
      * child_relid, or NULL if none.  The array itself is not allocated if
      * append_rel_list is empty.
      */
     struct AppendRelInfo **append_rel_array;
 
     /*
      * all_baserels is a Relids set of all base relids (but not "other"
      * relids) in the query; that is, the Relids identifier of the final join
      * we need to form.  This is computed in make_one_rel, just before we
      * start making Paths.
      */
     Relids      all_baserels;
 
     /*
      * nullable_baserels is a Relids set of base relids that are nullable by
      * some outer join in the jointree; these are rels that are potentially
      * nullable below the WHERE clause, SELECT targetlist, etc.  This is
      * computed in deconstruct_jointree.
      */
     Relids      nullable_baserels;
 
     /*
      * join_rel_list is a list of all join-relation RelOptInfos we have
      * considered in this planning run.  For small problems we just scan the
      * list to do lookups, but when there are many join relations we build a
      * hash table for faster lookups.  The hash table is present and valid
      * when join_rel_hash is not NULL.  Note that we still maintain the list
      * even when using the hash table for lookups; this simplifies life for
      * GEQO.
      */
     List       *join_rel_list;  /* list of join-relation RelOptInfos */
     struct HTAB *join_rel_hash; /* optional hashtable for join relations */
 
     /*
      * When doing a dynamic-programming-style join search, join_rel_level[k]
      * is a list of all join-relation RelOptInfos of level k, and
      * join_cur_level is the current level.  New join-relation RelOptInfos are
      * automatically added to the join_rel_level[join_cur_level] list.
      * join_rel_level is NULL if not in use.
      */
     List      **join_rel_level; /* lists of join-relation RelOptInfos */
     int         join_cur_level; /* index of list being extended */
 
     List       *init_plans;     /* init SubPlans for query */
 
     List       *cte_plan_ids;   /* per-CTE-item list of subplan IDs */
 
     List       *multiexpr_params;   /* List of Lists of Params for MULTIEXPR
                                      * subquery outputs */
 
     List       *eq_classes;     /* list of active EquivalenceClasses */
 
     List       *canon_pathkeys; /* list of "canonical" PathKeys */
 
     List       *left_join_clauses;  /* list of RestrictInfos for mergejoinable
                                      * outer join clauses w/nonnullable var on
                                      * left */
 
     List       *right_join_clauses; /* list of RestrictInfos for mergejoinable
                                      * outer join clauses w/nonnullable var on
                                      * right */
 
     List       *full_join_clauses;  /* list of RestrictInfos for mergejoinable
                                      * full join clauses */
 
     List       *join_info_list; /* list of SpecialJoinInfos */
 
     List       *append_rel_list;    /* list of AppendRelInfos */
 
     List       *rowMarks;       /* list of PlanRowMarks */
 
     List       *placeholder_list;   /* list of PlaceHolderInfos */
 
     List       *fkey_list;      /* list of ForeignKeyOptInfos */
 
     List       *query_pathkeys; /* desired pathkeys for query_planner() */
 
     List       *group_pathkeys; /* groupClause pathkeys, if any */
     List       *window_pathkeys;    /* pathkeys of bottom window, if any */
     List       *distinct_pathkeys;  /* distinctClause pathkeys, if any */
     List       *sort_pathkeys;  /* sortClause pathkeys, if any */
 
     List       *part_schemes;   /* Canonicalised partition schemes used in the
                                  * query. */
 
     List       *initial_rels;   /* RelOptInfos we are now trying to join */
 
     /* Use fetch_upper_rel() to get any particular upper rel */
     List       *upper_rels[UPPERREL_FINAL + 1]; /* upper-rel RelOptInfos */
 
     /* Result tlists chosen by grouping_planner for upper-stage processing */
     struct PathTarget *upper_targets[UPPERREL_FINAL + 1];//參見UpperRelationKind
 
     /*
      * grouping_planner passes back its final processed targetlist here, for
      * use in relabeling the topmost tlist of the finished Plan.
      */
     List       *processed_tlist;
 
     /* Fields filled during create_plan() for use in setrefs.c */
     AttrNumber *grouping_map;   /* for GroupingFunc fixup */
     List       *minmax_aggs;    /* List of MinMaxAggInfos */
 
     MemoryContext planner_cxt;  /* context holding PlannerInfo */
 
     double      total_table_pages;  /* # of pages in all tables of query */
 
     double      tuple_fraction; /* tuple_fraction passed to query_planner */
     double      limit_tuples;   /* limit_tuples passed to query_planner */
 
     Index       qual_security_level;    /* minimum security_level for quals */
     /* Note: qual_security_level is zero if there are no securityQuals */
 
     InheritanceKind inhTargetKind;  /* indicates if the target relation is an
                                      * inheritance child or partition or a
                                      * partitioned table */
     bool        hasJoinRTEs;    /* true if any RTEs are RTE_JOIN kind */
     bool        hasLateralRTEs; /* true if any RTEs are marked LATERAL */
     bool        hasDeletedRTEs; /* true if any RTE was deleted from jointree */
     bool        hasHavingQual;  /* true if havingQual was non-null */
     bool        hasPseudoConstantQuals; /* true if any RestrictInfo has
                                          * pseudoconstant = true */
     bool        hasRecursion;   /* true if planning a recursive WITH item */
 
     /* These fields are used only when hasRecursion is true: */
     int         wt_param_id;    /* PARAM_EXEC ID for the work table */
     struct Path *non_recursive_path;    /* a path for non-recursive term */
 
     /* These fields are workspace for createplan.c */
     Relids      curOuterRels;   /* outer rels above current node */
     List       *curOuterParams; /* not-yet-assigned NestLoopParams */
 
     /* optional private data for join_search_hook, e.g., GEQO */
     void       *join_search_private;
 
     /* Does this query modify any partition key columns? */
     bool        partColsUpdated;
 } PlannerInfo;
 
 /*
  * This enum identifies the different types of "upper" (post-scan/join)
  * relations that we might deal with during planning.
  */
 typedef enum UpperRelationKind
 {
     UPPERREL_SETOP,             /* result of UNION/INTERSECT/EXCEPT, if any */
     UPPERREL_PARTIAL_GROUP_AGG, /* result of partial grouping/aggregation, if
                                  * any */
     UPPERREL_GROUP_AGG,         /* result of grouping/aggregation, if any */
     UPPERREL_WINDOW,            /* result of window functions, if any */
     UPPERREL_DISTINCT,          /* result of "SELECT DISTINCT", if any */
     UPPERREL_ORDERED,           /* result of ORDER BY, if any */
     UPPERREL_FINAL              /* result of any remaining top-level actions */
     /* NB: UPPERREL_FINAL must be last enum entry; it's used to size arrays */
 } UpperRelationKind;
 

3、RangeTblEntry

 /*--------------------
  * RangeTblEntry -
  *    A range table is a List of RangeTblEntry nodes.
  *
  *    A range table entry may represent a plain relation, a sub-select in
  *    FROM, or the result of a JOIN clause.  (Only explicit JOIN syntax
  *    produces an RTE, not the implicit join resulting from multiple FROM
  *    items.  This is because we only need the RTE to deal with SQL features
  *    like outer joins and join-output-column aliasing.)  Other special
  *    RTE types also exist, as indicated by RTEKind.
  *
  *    Note that we consider RTE_RELATION to cover anything that has a pg_class
  *    entry.  relkind distinguishes the sub-cases.
  *
  *    alias is an Alias node representing the AS alias-clause attached to the
  *    FROM expression, or NULL if no clause.
  *
  *    eref is the table reference name and column reference names (either
  *    real or aliases).  Note that system columns (OID etc) are not included
  *    in the column list.
  *    eref->aliasname is required to be present, and should generally be used
  *    to identify the RTE for error messages etc.
  *
  *    In RELATION RTEs, the colnames in both alias and eref are indexed by
  *    physical attribute number; this means there must be colname entries for
  *    dropped columns.  When building an RTE we insert empty strings ("") for
  *    dropped columns.  Note however that a stored rule may have nonempty
  *    colnames for columns dropped since the rule was created (and for that
  *    matter the colnames might be out of date due to column renamings).
  *    The same comments apply to FUNCTION RTEs when a function's return type
  *    is a named composite type.
  *
  *    In JOIN RTEs, the colnames in both alias and eref are one-to-one with
  *    joinaliasvars entries.  A JOIN RTE will omit columns of its inputs when
  *    those columns are known to be dropped at parse time.  Again, however,
  *    a stored rule might contain entries for columns dropped since the rule
  *    was created.  (This is only possible for columns not actually referenced
  *    in the rule.)  When loading a stored rule, we replace the joinaliasvars
  *    items for any such columns with null pointers.  (We can't simply delete
  *    them from the joinaliasvars list, because that would affect the attnums
  *    of Vars referencing the rest of the list.)
  *
  *    inh is true for relation references that should be expanded to include
  *    inheritance children, if the rel has any.  This *must* be false for
  *    RTEs other than RTE_RELATION entries.
  *
  *    inFromCl marks those range variables that are listed in the FROM clause.
  *    It's false for RTEs that are added to a query behind the scenes, such
  *    as the NEW and OLD variables for a rule, or the subqueries of a UNION.
  *    This flag is not used anymore during parsing, since the parser now uses
  *    a separate "namespace" data structure to control visibility, but it is
  *    needed by ruleutils.c to determine whether RTEs should be shown in
  *    decompiled queries.
  *
  *    requiredPerms and checkAsUser specify run-time access permissions
  *    checks to be performed at query startup.  The user must have *all*
  *    of the permissions that are OR'd together in requiredPerms (zero
  *    indicates no permissions checking).  If checkAsUser is not zero,
  *    then do the permissions checks using the access rights of that user,
  *    not the current effective user ID.  (This allows rules to act as
  *    setuid gateways.)  Permissions checks only apply to RELATION RTEs.
  *
  *    For SELECT/INSERT/UPDATE permissions, if the user doesn't have
  *    table-wide permissions then it is sufficient to have the permissions
  *    on all columns identified in selectedCols (for SELECT) and/or
  *    insertedCols and/or updatedCols (INSERT with ON CONFLICT DO UPDATE may
  *    have all 3).  selectedCols, insertedCols and updatedCols are bitmapsets,
  *    which cannot have negative integer members, so we subtract
  *    FirstLowInvalidHeapAttributeNumber from column numbers before storing
  *    them in these fields.  A whole-row Var reference is represented by
  *    setting the bit for InvalidAttrNumber.
  *
  *    securityQuals is a list of security barrier quals (boolean expressions),
  *    to be tested in the listed order before returning a row from the
  *    relation.  It is always NIL in parser output.  Entries are added by the
  *    rewriter to implement security-barrier views and/or row-level security.
  *    Note that the planner turns each boolean expression into an implicitly
  *    AND'ed sublist, as is its usual habit with qualification expressions.
  *--------------------
  */
 typedef enum RTEKind
 {
     RTE_RELATION,               /* ordinary relation reference */
     RTE_SUBQUERY,               /* subquery in FROM */
     RTE_JOIN,                   /* join */
     RTE_FUNCTION,               /* function in FROM */
     RTE_TABLEFUNC,              /* TableFunc(.., column list) */
     RTE_VALUES,                 /* VALUES (<exprlist>), (<exprlist>), ... */
     RTE_CTE,                    /* common table expr (WITH list element) */
     RTE_NAMEDTUPLESTORE         /* tuplestore, e.g. for AFTER triggers */
 } RTEKind;
 
 typedef struct RangeTblEntry
 {
     NodeTag     type;
 
     RTEKind     rtekind;        /* see above */
 
     /*
      * XXX the fields applicable to only some rte kinds should be merged into
      * a union.  I didn't do this yet because the diffs would impact a lot of
      * code that is being actively worked on.  FIXME someday.
      */
 
     /*
      * Fields valid for a plain relation RTE (else zero):
      *
      * As a special case, RTE_NAMEDTUPLESTORE can also set relid to indicate
      * that the tuple format of the tuplestore is the same as the referenced
      * relation.  This allows plans referencing AFTER trigger transition
      * tables to be invalidated if the underlying table is altered.
      */
     Oid         relid;          /* OID of the relation */
     char        relkind;        /* relation kind (see pg_class.relkind) */
     struct TableSampleClause *tablesample;  /* sampling info, or NULL */
 
     /*
      * Fields valid for a subquery RTE (else NULL):
      */
     Query      *subquery;       /* the sub-query */
     bool        security_barrier;   /* is from security_barrier view? */
 
     /*
      * Fields valid for a join RTE (else NULL/zero):
      *
      * joinaliasvars is a list of (usually) Vars corresponding to the columns
      * of the join result.  An alias Var referencing column K of the join
      * result can be replaced by the K'th element of joinaliasvars --- but to
      * simplify the task of reverse-listing aliases correctly, we do not do
      * that until planning time.  In detail: an element of joinaliasvars can
      * be a Var of one of the join's input relations, or such a Var with an
      * implicit coercion to the join's output column type, or a COALESCE
      * expression containing the two input column Vars (possibly coerced).
      * Within a Query loaded from a stored rule, it is also possible for
      * joinaliasvars items to be null pointers, which are placeholders for
      * (necessarily unreferenced) columns dropped since the rule was made.
      * Also, once planning begins, joinaliasvars items can be almost anything,
      * as a result of subquery-flattening substitutions.
      */
     JoinType    jointype;       /* type of join */
     List       *joinaliasvars;  /* list of alias-var expansions */
 
     /*
      * Fields valid for a function RTE (else NIL/zero):
      *
      * When funcordinality is true, the eref->colnames list includes an alias
      * for the ordinality column.  The ordinality column is otherwise
      * implicit, and must be accounted for "by hand" in places such as
      * expandRTE().
      */
     List       *functions;      /* list of RangeTblFunction nodes */
     bool        funcordinality; /* is this called WITH ORDINALITY? */
 
     /*
      * Fields valid for a TableFunc RTE (else NULL):
      */
     TableFunc  *tablefunc;
 
     /*
      * Fields valid for a values RTE (else NIL):
      */
     List       *values_lists;   /* list of expression lists */
 
     /*
      * Fields valid for a CTE RTE (else NULL/zero):
      */
     char       *ctename;        /* name of the WITH list item */
     Index       ctelevelsup;    /* number of query levels up */
     bool        self_reference; /* is this a recursive self-reference? */
 
     /*
      * Fields valid for table functions, values, CTE and ENR RTEs (else NIL):
      *
      * We need these for CTE RTEs so that the types of self-referential
      * columns are well-defined.  For VALUES RTEs, storing these explicitly
      * saves having to re-determine the info by scanning the values_lists. For
      * ENRs, we store the types explicitly here (we could get the information
      * from the catalogs if 'relid' was supplied, but we'd still need these
      * for TupleDesc-based ENRs, so we might as well always store the type
      * info here).
      *
      * For ENRs only, we have to consider the possibility of dropped columns.
      * A dropped column is included in these lists, but it will have zeroes in
      * all three lists (as well as an empty-string entry in eref).  Testing
      * for zero coltype is the standard way to detect a dropped column.
      */
     List       *coltypes;       /* OID list of column type OIDs */
     List       *coltypmods;     /* integer list of column typmods */
     List       *colcollations;  /* OID list of column collation OIDs */
 
     /*
      * Fields valid for ENR RTEs (else NULL/zero):
      */
     char       *enrname;        /* name of ephemeral named relation */
     double      enrtuples;      /* estimated or actual from caller */
 
     /*
      * Fields valid in all RTEs:
      */
     Alias      *alias;          /* user-written alias clause, if any */
     Alias      *eref;           /* expanded reference names */
     bool        lateral;        /* subquery, function, or values is LATERAL? */
     bool        inh;            /* inheritance requested? */
     bool        inFromCl;       /* present in FROM clause? */
     AclMode     requiredPerms;  /* bitmask of required access permissions */
     Oid         checkAsUser;    /* if valid, check access as this role */
     Bitmapset  *selectedCols;   /* columns needing SELECT permission */
     Bitmapset  *insertedCols;   /* columns needing INSERT permission */
     Bitmapset  *updatedCols;    /* columns needing UPDATE permission */
     List       *securityQuals;  /* security barrier quals to apply, if any */
 } RangeTblEntry;
 

4、TargetEntry

 /*--------------------
  * TargetEntry -
  *     a target entry (used in query target lists)
  *
  * Strictly speaking, a TargetEntry isn't an expression node (since it can't
  * be evaluated by ExecEvalExpr).  But we treat it as one anyway, since in
  * very many places it's convenient to process a whole query targetlist as a
  * single expression tree.
  *
  * In a SELECT's targetlist, resno should always be equal to the item's
  * ordinal position (counting from 1).  However, in an INSERT or UPDATE
  * targetlist, resno represents the attribute number of the destination
  * column for the item; so there may be missing or out-of-order resnos.
  * It is even legal to have duplicated resnos; consider
  *      UPDATE table SET arraycol[1] = ..., arraycol[2] = ..., ...
  * The two meanings come together in the executor, because the planner
  * transforms INSERT/UPDATE tlists into a normalized form with exactly
  * one entry for each column of the destination table.  Before that's
  * happened, however, it is risky to assume that resno == position.
  * Generally get_tle_by_resno() should be used rather than list_nth()
  * to fetch tlist entries by resno, and only in SELECT should you assume
  * that resno is a unique identifier.
  *
  * resname is required to represent the correct column name in non-resjunk
  * entries of top-level SELECT targetlists, since it will be used as the
  * column title sent to the frontend.  In most other contexts it is only
  * a debugging aid, and may be wrong or even NULL.  (In particular, it may
  * be wrong in a tlist from a stored rule, if the referenced column has been
  * renamed by ALTER TABLE since the rule was made.  Also, the planner tends
  * to store NULL rather than look up a valid name for tlist entries in
  * non-toplevel plan nodes.)  In resjunk entries, resname should be either
  * a specific system-generated name (such as "ctid") or NULL; anything else
  * risks confusing ExecGetJunkAttribute!
  *
  * ressortgroupref is used in the representation of ORDER BY, GROUP BY, and
  * DISTINCT items.  Targetlist entries with ressortgroupref=0 are not
  * sort/group items.  If ressortgroupref>0, then this item is an ORDER BY,
  * GROUP BY, and/or DISTINCT target value.  No two entries in a targetlist
  * may have the same nonzero ressortgroupref --- but there is no particular
  * meaning to the nonzero values, except as tags.  (For example, one must
  * not assume that lower ressortgroupref means a more significant sort key.)
  * The order of the associated SortGroupClause lists determine the semantics.
  *
  * resorigtbl/resorigcol identify the source of the column, if it is a
  * simple reference to a column of a base table (or view).  If it is not
  * a simple reference, these fields are zeroes.
  *
  * If resjunk is true then the column is a working column (such as a sort key)
  * that should be removed from the final output of the query.  Resjunk columns
  * must have resnos that cannot duplicate any regular column's resno.  Also
  * note that there are places that assume resjunk columns come after non-junk
  * columns.
  *--------------------
  */
 typedef struct TargetEntry
 {
     Expr        xpr;
     Expr       *expr;           /* expression to evaluate */
     AttrNumber  resno;          /* attribute number (see notes above) */
     char       *resname;        /* name of the column (could be NULL) */
     Index       ressortgroupref;    /* nonzero if referenced by a sort/group
                                      * clause */
     Oid         resorigtbl;     /* OID of column's source table */
     AttrNumber  resorigcol;     /* column's number in source table */
     bool        resjunk;        /* set to true to eliminate the attribute from
                                  * final target list */
 } TargetEntry;
  

5、RelOptInfo

 /*----------
  * RelOptInfo
  *      Per-relation information for planning/optimization
  *
  * For planning purposes, a "base rel" is either a plain relation (a table)
  * or the output of a sub-SELECT or function that appears in the range table.
  * In either case it is uniquely identified by an RT index.  A "joinrel"
  * is the joining of two or more base rels.  A joinrel is identified by
  * the set of RT indexes for its component baserels.  We create RelOptInfo
  * nodes for each baserel and joinrel, and store them in the PlannerInfo's
  * simple_rel_array and join_rel_list respectively.
  *
  * Note that there is only one joinrel for any given set of component
  * baserels, no matter what order we assemble them in; so an unordered
  * set is the right datatype to identify it with.
  *
  * We also have "other rels", which are like base rels in that they refer to
  * single RT indexes; but they are not part of the join tree, and are given
  * a different RelOptKind to identify them.
  * Currently the only kind of otherrels are those made for member relations
  * of an "append relation", that is an inheritance set or UNION ALL subquery.
  * An append relation has a parent RTE that is a base rel, which represents
  * the entire append relation.  The member RTEs are otherrels.  The parent
  * is present in the query join tree but the members are not.  The member
  * RTEs and otherrels are used to plan the scans of the individual tables or
  * subqueries of the append set; then the parent baserel is given Append
  * and/or MergeAppend paths comprising the best paths for the individual
  * member rels.  (See comments for AppendRelInfo for more information.)
  *
  * At one time we also made otherrels to represent join RTEs, for use in
  * handling join alias Vars.  Currently this is not needed because all join
  * alias Vars are expanded to non-aliased form during preprocess_expression.
  *
  * We also have relations representing joins between child relations of
  * different partitioned tables. These relations are not added to
  * join_rel_level lists as they are not joined directly by the dynamic
  * programming algorithm.
  *
  * There is also a RelOptKind for "upper" relations, which are RelOptInfos
  * that describe post-scan/join processing steps, such as aggregation.
  * Many of the fields in these RelOptInfos are meaningless, but their Path
  * fields always hold Paths showing ways to do that processing step.
  *
  * Lastly, there is a RelOptKind for "dead" relations, which are base rels
  * that we have proven we don't need to join after all.
  *
  * Parts of this data structure are specific to various scan and join
  * mechanisms.  It didn't seem worth creating new node types for them.
  *
  *      relids - Set of base-relation identifiers; it is a base relation
  *              if there is just one, a join relation if more than one
  *      rows - estimated number of tuples in the relation after restriction
  *             clauses have been applied (ie, output rows of a plan for it)
  *      consider_startup - true if there is any value in keeping plain paths for
  *                         this rel on the basis of having cheap startup cost
  *      consider_param_startup - the same for parameterized paths
  *      reltarget - Default Path output tlist for this rel; normally contains
  *                  Var and PlaceHolderVar nodes for the values we need to
  *                  output from this relation.
  *                  List is in no particular order, but all rels of an
  *                  appendrel set must use corresponding orders.
  *                  NOTE: in an appendrel child relation, may contain
  *                  arbitrary expressions pulled up from a subquery!
  *      pathlist - List of Path nodes, one for each potentially useful
  *                 method of generating the relation
  *      ppilist - ParamPathInfo nodes for parameterized Paths, if any
  *      cheapest_startup_path - the pathlist member with lowest startup cost
  *          (regardless of ordering) among the unparameterized paths;
  *          or NULL if there is no unparameterized path
  *      cheapest_total_path - the pathlist member with lowest total cost
  *          (regardless of ordering) among the unparameterized paths;
  *          or if there is no unparameterized path, the path with lowest
  *          total cost among the paths with minimum parameterization
  *      cheapest_unique_path - for caching cheapest path to produce unique
  *          (no duplicates) output from relation; NULL if not yet requested
  *      cheapest_parameterized_paths - best paths for their parameterizations;
  *          always includes cheapest_total_path, even if that's unparameterized
  *      direct_lateral_relids - rels this rel has direct LATERAL references to
  *      lateral_relids - required outer rels for LATERAL, as a Relids set
  *          (includes both direct and indirect lateral references)
  *
  * If the relation is a base relation it will have these fields set:
  *
  *      relid - RTE index (this is redundant with the relids field, but
  *              is provided for convenience of access)
  *      rtekind - copy of RTE's rtekind field
  *      min_attr, max_attr - range of valid AttrNumbers for rel
  *      attr_needed - array of bitmapsets indicating the highest joinrel
  *              in which each attribute is needed; if bit 0 is set then
  *              the attribute is needed as part of final targetlist
  *      attr_widths - cache space for per-attribute width estimates;
  *                    zero means not computed yet
  *      lateral_vars - lateral cross-references of rel, if any (list of
  *                     Vars and PlaceHolderVars)
  *      lateral_referencers - relids of rels that reference this one laterally
  *              (includes both direct and indirect lateral references)
  *      indexlist - list of IndexOptInfo nodes for relation's indexes
  *                  (always NIL if it's not a table)
  *      pages - number of disk pages in relation (zero if not a table)
  *      tuples - number of tuples in relation (not considering restrictions)
  *      allvisfrac - fraction of disk pages that are marked all-visible
  *      subroot - PlannerInfo for subquery (NULL if it's not a subquery)
  *      subplan_params - list of PlannerParamItems to be passed to subquery
  *
  *      Note: for a subquery, tuples and subroot are not set immediately
  *      upon creation of the RelOptInfo object; they are filled in when
  *      set_subquery_pathlist processes the object.
  *
  *      For otherrels that are appendrel members, these fields are filled
  *      in just as for a baserel, except we don't bother with lateral_vars.
  *
  * If the relation is either a foreign table or a join of foreign tables that
  * all belong to the same foreign server and are assigned to the same user to
  * check access permissions as (cf checkAsUser), these fields will be set:
  *
  *      serverid - OID of foreign server, if foreign table (else InvalidOid)
  *      userid - OID of user to check access as (InvalidOid means current user)
  *      useridiscurrent - we've assumed that userid equals current user
  *      fdwroutine - function hooks for FDW, if foreign table (else NULL)
  *      fdw_private - private state for FDW, if foreign table (else NULL)
  *
  * Two fields are used to cache knowledge acquired during the join search
  * about whether this rel is provably unique when being joined to given other
  * relation(s), ie, it can have at most one row matching any given row from
  * that join relation.  Currently we only attempt such proofs, and thus only
  * populate these fields, for base rels; but someday they might be used for
  * join rels too:
  *
  *      unique_for_rels - list of Relid sets, each one being a set of other
  *                  rels for which this one has been proven unique
  *      non_unique_for_rels - list of Relid sets, each one being a set of
  *                  other rels for which we have tried and failed to prove
  *                  this one unique
  *
  * The presence of the following fields depends on the restrictions
  * and joins that the relation participates in:
  *
  *      baserestrictinfo - List of RestrictInfo nodes, containing info about
  *                  each non-join qualification clause in which this relation
  *                  participates (only used for base rels)
  *      baserestrictcost - Estimated cost of evaluating the baserestrictinfo
  *                  clauses at a single tuple (only used for base rels)
  *      baserestrict_min_security - Smallest security_level found among
  *                  clauses in baserestrictinfo
  *      joininfo  - List of RestrictInfo nodes, containing info about each
  *                  join clause in which this relation participates (but
  *                  note this excludes clauses that might be derivable from
  *                  EquivalenceClasses)
  *      has_eclass_joins - flag that EquivalenceClass joins are possible
  *
  * Note: Keeping a restrictinfo list in the RelOptInfo is useful only for
  * base rels, because for a join rel the set of clauses that are treated as
  * restrict clauses varies depending on which sub-relations we choose to join.
  * (For example, in a 3-base-rel join, a clause relating rels 1 and 2 must be
  * treated as a restrictclause if we join {1} and {2 3} to make {1 2 3}; but
  * if we join {1 2} and {3} then that clause will be a restrictclause in {1 2}
  * and should not be processed again at the level of {1 2 3}.)  Therefore,
  * the restrictinfo list in the join case appears in individual JoinPaths
  * (field joinrestrictinfo), not in the parent relation.  But it's OK for
  * the RelOptInfo to store the joininfo list, because that is the same
  * for a given rel no matter how we form it.
  *
  * We store baserestrictcost in the RelOptInfo (for base relations) because
  * we know we will need it at least once (to price the sequential scan)
  * and may need it multiple times to price index scans.
  *
  * If the relation is partitioned, these fields will be set:
  *
  *      part_scheme - Partitioning scheme of the relation
  *      nparts - Number of partitions
  *      boundinfo - Partition bounds
  *      partition_qual - Partition constraint if not the root
  *      part_rels - RelOptInfos for each partition
  *      partexprs, nullable_partexprs - Partition key expressions
  *      partitioned_child_rels - RT indexes of unpruned partitions of
  *                               this relation that are partitioned tables
  *                               themselves, in hierarchical order
  *
  * Note: A base relation always has only one set of partition keys, but a join
  * relation may have as many sets of partition keys as the number of relations
  * being joined. partexprs and nullable_partexprs are arrays containing
  * part_scheme->partnatts elements each. Each of these elements is a list of
  * partition key expressions.  For a base relation each list in partexprs
  * contains only one expression and nullable_partexprs is not populated. For a
  * join relation, partexprs and nullable_partexprs contain partition key
  * expressions from non-nullable and nullable relations resp. Lists at any
  * given position in those arrays together contain as many elements as the
  * number of joining relations.
  *----------
  */
 typedef enum RelOptKind
 {
     RELOPT_BASEREL,
     RELOPT_JOINREL,
     RELOPT_OTHER_MEMBER_REL,
     RELOPT_OTHER_JOINREL,
     RELOPT_UPPER_REL,
     RELOPT_OTHER_UPPER_REL,
     RELOPT_DEADREL
 } RelOptKind;
 
 /*
  * Is the given relation a simple relation i.e a base or "other" member
  * relation?
  */
 #define IS_SIMPLE_REL(rel) \
     ((rel)->reloptkind == RELOPT_BASEREL || \
      (rel)->reloptkind == RELOPT_OTHER_MEMBER_REL)
 
 /* Is the given relation a join relation? */
 #define IS_JOIN_REL(rel)    \
     ((rel)->reloptkind == RELOPT_JOINREL || \
      (rel)->reloptkind == RELOPT_OTHER_JOINREL)
 
 /* Is the given relation an upper relation? */
 #define IS_UPPER_REL(rel)   \
     ((rel)->reloptkind == RELOPT_UPPER_REL || \
      (rel)->reloptkind == RELOPT_OTHER_UPPER_REL)
 
 /* Is the given relation an "other" relation? */
 #define IS_OTHER_REL(rel) \
     ((rel)->reloptkind == RELOPT_OTHER_MEMBER_REL || \
      (rel)->reloptkind == RELOPT_OTHER_JOINREL || \
      (rel)->reloptkind == RELOPT_OTHER_UPPER_REL)
 
 typedef struct RelOptInfo
 {
     NodeTag     type;
 
     RelOptKind  reloptkind;
 
     /* all relations included in this RelOptInfo */
     Relids      relids;         /* set of base relids (rangetable indexes) */
 
     /* size estimates generated by planner */
     double      rows;           /* estimated number of result tuples */
 
     /* per-relation planner control flags */
     bool        consider_startup;   /* keep cheap-startup-cost paths? */
     bool        consider_param_startup; /* ditto, for parameterized paths? */
     bool        consider_parallel;  /* consider parallel paths? */
 
     /* default result targetlist for Paths scanning this relation */
     struct PathTarget *reltarget;   /* list of Vars/Exprs, cost, width */
 
     /* materialization information */
     List       *pathlist;       /* Path structures */
     List       *ppilist;        /* ParamPathInfos used in pathlist */
     List       *partial_pathlist;   /* partial Paths */
     struct Path *cheapest_startup_path;
     struct Path *cheapest_total_path;
     struct Path *cheapest_unique_path;
     List       *cheapest_parameterized_paths;
 
     /* parameterization information needed for both base rels and join rels */
     /* (see also lateral_vars and lateral_referencers) */
     Relids      direct_lateral_relids;  /* rels directly laterally referenced */
     Relids      lateral_relids; /* minimum parameterization of rel */
 
     /* information about a base rel (not set for join rels!) */
     Index       relid;
     Oid         reltablespace;  /* containing tablespace */
     RTEKind     rtekind;        /* RELATION, SUBQUERY, FUNCTION, etc */
     AttrNumber  min_attr;       /* smallest attrno of rel (often <0) */
     AttrNumber  max_attr;       /* largest attrno of rel */
     Relids     *attr_needed;    /* array indexed [min_attr .. max_attr] */
     int32      *attr_widths;    /* array indexed [min_attr .. max_attr] */
     List       *lateral_vars;   /* LATERAL Vars and PHVs referenced by rel */
     Relids      lateral_referencers;    /* rels that reference me laterally */
     List       *indexlist;      /* list of IndexOptInfo */
     List       *statlist;       /* list of StatisticExtInfo */
     BlockNumber pages;          /* size estimates derived from pg_class */
     double      tuples;
     double      allvisfrac;
     PlannerInfo *subroot;       /* if subquery */
     List       *subplan_params; /* if subquery */
     int         rel_parallel_workers;   /* wanted number of parallel workers */
 
     /* Information about foreign tables and foreign joins */
     Oid         serverid;       /* identifies server for the table or join */
     Oid         userid;         /* identifies user to check access as */
     bool        useridiscurrent;    /* join is only valid for current user */
     /* use "struct FdwRoutine" to avoid including fdwapi.h here */
     struct FdwRoutine *fdwroutine;
     void       *fdw_private;
 
     /* cache space for remembering if we have proven this relation unique */
     List       *unique_for_rels;    /* known unique for these other relid
                                      * set(s) */
     List       *non_unique_for_rels;    /* known not unique for these set(s) */
 
     /* used by various scans and joins: */
     List       *baserestrictinfo;   /* RestrictInfo structures (if base rel) */
     QualCost    baserestrictcost;   /* cost of evaluating the above */
     Index       baserestrict_min_security;  /* min security_level found in
                                              * baserestrictinfo */
     List       *joininfo;       /* RestrictInfo structures for join clauses
                                  * involving this rel */
     bool        has_eclass_joins;   /* T means joininfo is incomplete */
 
     /* used by "other" relations */
     Relids      top_parent_relids;  /* Relids of topmost parents */
 
     /* used for partitioned relations */
     PartitionScheme part_scheme;    /* Partitioning scheme. */
     int         nparts;         /* number of partitions */
     struct PartitionBoundInfoData *boundinfo;   /* Partition bounds */
     List       *partition_qual; /* partition constraint */
     struct RelOptInfo **part_rels;  /* Array of RelOptInfos of partitions,
                                      * stored in the same order of bounds */
     List      **partexprs;      /* Non-nullable partition key expressions. */
     List      **nullable_partexprs; /* Nullable partition key expressions. */
     List       *partitioned_child_rels; /* List of RT indexes. */
 } RelOptInfo;
 

6、Path

 /*
  * Type "Path" is used as-is for sequential-scan paths, as well as some other
  * simple plan types that we don't need any extra information in the path for.
  * For other path types it is the first component of a larger struct.
  *
  * "pathtype" is the NodeTag of the Plan node we could build from this Path.
  * It is partially redundant with the Path's NodeTag, but allows us to use
  * the same Path type for multiple Plan types when there is no need to
  * distinguish the Plan type during path processing.
  *
  * "parent" identifies the relation this Path scans, and "pathtarget"
  * describes the precise set of output columns the Path would compute.
  * In simple cases all Paths for a given rel share the same targetlist,
  * which we represent by having path->pathtarget equal to parent->reltarget.
  *
  * "param_info", if not NULL, links to a ParamPathInfo that identifies outer
  * relation(s) that provide parameter values to each scan of this path.
  * That means this path can only be joined to those rels by means of nestloop
  * joins with this path on the inside.  Also note that a parameterized path
  * is responsible for testing all "movable" joinclauses involving this rel
  * and the specified outer rel(s).
  *
  * "rows" is the same as parent->rows in simple paths, but in parameterized
  * paths and UniquePaths it can be less than parent->rows, reflecting the
  * fact that we've filtered by extra join conditions or removed duplicates.
  *
  * "pathkeys" is a List of PathKey nodes (see above), describing the sort
  * ordering of the path's output rows.
  */
 typedef struct Path
 {
     NodeTag     type;
 
     NodeTag     pathtype;       /* tag identifying scan/join method */
 
     RelOptInfo *parent;         /* the relation this path can build */
     PathTarget *pathtarget;     /* list of Vars/Exprs, cost, width */
 
     ParamPathInfo *param_info;  /* parameterization info, or NULL if none */
 
     bool        parallel_aware; /* engage parallel-aware logic? */
     bool        parallel_safe;  /* OK to use as part of parallel plan? */
     int         parallel_workers;   /* desired # of workers; 0 = not parallel */
 
     /* estimated size/costs for path (see costsize.c for more info) */
     double      rows;           /* estimated number of result tuples */
     Cost        startup_cost;   /* cost expended before fetching any tuples */
     Cost        total_cost;     /* total cost (assuming all tuples fetched) */
 
     List       *pathkeys;       /* sort ordering of path's output */
     /* pathkeys is a List of PathKey nodes; see above */
 } Path;
 
/*
  * PathKeys
  *
  * The sort ordering of a path is represented by a list of PathKey nodes.
  * An empty list implies no known ordering.  Otherwise the first item
  * represents the primary sort key, the second the first secondary sort key,
  * etc.  The value being sorted is represented by linking to an
  * EquivalenceClass containing that value and including pk_opfamily among its
  * ec_opfamilies.  The EquivalenceClass tells which collation to use, too.
  * This is a convenient method because it makes it trivial to detect
  * equivalent and closely-related orderings. (See optimizer/README for more
  * information.)
  *
  * Note: pk_strategy is either BTLessStrategyNumber (for ASC) or
  * BTGreaterStrategyNumber (for DESC).  We assume that all ordering-capable
  * index types will use btree-compatible strategy numbers.
  */
 typedef struct PathKey
 {
     NodeTag     type;
 
     EquivalenceClass *pk_eclass;    /* the value that is ordered */
     Oid         pk_opfamily;    /* btree opfamily defining the ordering */
     int         pk_strategy;    /* sort direction (ASC or DESC) */
     bool        pk_nulls_first; /* do NULLs come before normal values? */
 } PathKey;
 
 
 
 /*
  * PathTarget
  *
  * This struct contains what we need to know during planning about the
  * targetlist (output columns) that a Path will compute.  Each RelOptInfo
  * includes a default PathTarget, which its individual Paths may simply
  * reference.  However, in some cases a Path may compute outputs different
  * from other Paths, and in that case we make a custom PathTarget for it.
  * For example, an indexscan might return index expressions that would
  * otherwise need to be explicitly calculated.  (Note also that "upper"
  * relations generally don't have useful default PathTargets.)
  *
  * exprs contains bare expressions; they do not have TargetEntry nodes on top,
  * though those will appear in finished Plans.
  *
  * sortgrouprefs[] is an array of the same length as exprs, containing the
  * corresponding sort/group refnos, or zeroes for expressions not referenced
  * by sort/group clauses.  If sortgrouprefs is NULL (which it generally is in
  * RelOptInfo.reltarget targets; only upper-level Paths contain this info),
  * we have not identified sort/group columns in this tlist.  This allows us to
  * deal with sort/group refnos when needed with less expense than including
  * TargetEntry nodes in the exprs list.
  */
 typedef struct PathTarget
 {
     NodeTag     type;
     List       *exprs;          /* list of expressions to be computed */
     Index      *sortgrouprefs;  /* corresponding sort/group refnos, or 0 */
     QualCost    cost;           /* cost of evaluating the expressions */
     int         width;          /* estimated avg width of result tuples */
 } PathTarget;
 
 /* Convenience macro to get a sort/group refno from a PathTarget */
 #define get_pathtarget_sortgroupref(target, colno) \
     ((target)->sortgrouprefs ? (target)->sortgrouprefs[colno] : (Index) 0)


7、ModifyTable

 /* ----------------
  *   ModifyTable node -
  *      Apply rows produced by subplan(s) to result table(s),
  *      by inserting, updating, or deleting.
  *
  * Note that rowMarks and epqParam are presumed to be valid for all the
  * subplan(s); they can't contain any info that varies across subplans.
  * ----------------
  */
 typedef struct ModifyTable
 {
     Plan        plan;
     CmdType     operation;      /* INSERT, UPDATE, or DELETE */
     bool        canSetTag;      /* do we set the command tag/es_processed? */
     Index       nominalRelation;    /* Parent RT index for use of EXPLAIN */
     /* RT indexes of non-leaf tables in a partition tree */
     List       *partitioned_rels;
     bool        partColsUpdated;    /* some part key in hierarchy updated */
     List       *resultRelations;    /* integer list of RT indexes */
     int         resultRelIndex; /* index of first resultRel in plan's list */
     int         rootResultRelIndex; /* index of the partitioned table root */
     List       *plans;          /* plan(s) producing source data */
     List       *withCheckOptionLists;   /* per-target-table WCO lists */
     List       *returningLists; /* per-target-table RETURNING tlists */
     List       *fdwPrivLists;   /* per-target-table FDW private data lists */
     Bitmapset  *fdwDirectModifyPlans;   /* indices of FDW DM plans */
     List       *rowMarks;       /* PlanRowMarks (non-locking only) */
     int         epqParam;       /* ID of Param for EvalPlanQual re-eval */
     OnConflictAction onConflictAction;  /* ON CONFLICT action */
     List       *arbiterIndexes; /* List of ON CONFLICT arbiter index OIDs  */
     List       *onConflictSet;  /* SET for INSERT ON CONFLICT DO UPDATE */
     Node       *onConflictWhere;    /* WHERE for ON CONFLICT UPDATE */
     Index       exclRelRTI;     /* RTI of the EXCLUDED pseudo relation */
     List       *exclRelTlist;   /* tlist of the EXCLUDED pseudo relation */
 } ModifyTable;

依賴的函式
1、grouping_planner

/*--------------------
  * grouping_planner
  *    Perform planning steps related to grouping, aggregation, etc.
  *
  * This function adds all required top-level processing to the scan/join
  * Path(s) produced by query_planner.
  *
  * If inheritance_update is true, we're being called from inheritance_planner
  * and should not include a ModifyTable step in the resulting Path(s).
  * (inheritance_planner will create a single ModifyTable node covering all the
  * target tables.)
  *
  * tuple_fraction is the fraction of tuples we expect will be retrieved.
  * tuple_fraction is interpreted as follows:
  *    0: expect all tuples to be retrieved (normal case)
  *    0 < tuple_fraction < 1: expect the given fraction of tuples available
  *      from the plan to be retrieved
  *    tuple_fraction >= 1: tuple_fraction is the absolute number of tuples
  *      expected to be retrieved (ie, a LIMIT specification)
  *
  * Returns nothing; the useful output is in the Paths we attach to the
  * (UPPERREL_FINAL, NULL) upperrel in *root.  In addition,
  * root->processed_tlist contains the final processed targetlist.
  *
  * Note that we have not done set_cheapest() on the final rel; it's convenient
  * to leave this to the caller.
  *--------------------
  */
 static void
 grouping_planner(PlannerInfo *root, bool inheritance_update,
                  double tuple_fraction)
 {
     Query      *parse = root->parse;
     List       *tlist;
     int64       offset_est = 0;
     int64       count_est = 0;
     double      limit_tuples = -1.0;
     bool        have_postponed_srfs = false;
     PathTarget *final_target;
     List       *final_targets;
     List       *final_targets_contain_srfs;
     bool        final_target_parallel_safe;
     RelOptInfo *current_rel;
     RelOptInfo *final_rel;
     ListCell   *lc;
 
     /* Tweak caller-supplied tuple_fraction if have LIMIT/OFFSET */
     if (parse->limitCount || parse->limitOffset)
     {
         tuple_fraction = preprocess_limit(root, tuple_fraction,
                                           &offset_est, &count_est);
 
         /*
          * If we have a known LIMIT, and don't have an unknown OFFSET, we can
          * estimate the effects of using a bounded sort.
          */
         if (count_est > 0 && offset_est >= 0)
             limit_tuples = (double) count_est + (double) offset_est;
     }
 
     /* Make tuple_fraction accessible to lower-level routines */
     root->tuple_fraction = tuple_fraction;
 
     if (parse->setOperations)
     {
         /*
          * If there's a top-level ORDER BY, assume we have to fetch all the
          * tuples.  This might be too simplistic given all the hackery below
          * to possibly avoid the sort; but the odds of accurate estimates here
          * are pretty low anyway.  XXX try to get rid of this in favor of
          * letting plan_set_operations generate both fast-start and
          * cheapest-total paths.
          */
         if (parse->sortClause)
             root->tuple_fraction = 0.0;
 
         /*
          * Construct Paths for set operations.  The results will not need any
          * work except perhaps a top-level sort and/or LIMIT.  Note that any
          * special work for recursive unions is the responsibility of
          * plan_set_operations.
          */
         current_rel = plan_set_operations(root);
 
         /*
          * We should not need to call preprocess_targetlist, since we must be
          * in a SELECT query node.  Instead, use the targetlist returned by
          * plan_set_operations (since this tells whether it returned any
          * resjunk columns!), and transfer any sort key information from the
          * original tlist.
          */
         Assert(parse->commandType == CMD_SELECT);
 
         tlist = root->processed_tlist;  /* from plan_set_operations */
 
         /* for safety, copy processed_tlist instead of modifying in-place */
         tlist = postprocess_setop_tlist(copyObject(tlist), parse->targetList);
 
         /* Save aside the final decorated tlist */
         root->processed_tlist = tlist;
 
         /* Also extract the PathTarget form of the setop result tlist */
         final_target = current_rel->cheapest_total_path->pathtarget;
 
         /* And check whether it's parallel safe */
         final_target_parallel_safe =
             is_parallel_safe(root, (Node *) final_target->exprs);
 
         /* The setop result tlist couldn't contain any SRFs */
         Assert(!parse->hasTargetSRFs);
         final_targets = final_targets_contain_srfs = NIL;
 
         /*
          * Can't handle FOR [KEY] UPDATE/SHARE here (parser should have
          * checked already, but let's make sure).
          */
         if (parse->rowMarks)
             ereport(ERROR,
                     (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             /*------
               translator: %s is a SQL row locking clause such as FOR UPDATE */
                      errmsg("%s is not allowed with UNION/INTERSECT/EXCEPT",
                             LCS_asString(linitial_node(RowMarkClause,
                                                        parse->rowMarks)->strength))));
 
         /*
          * Calculate pathkeys that represent result ordering requirements
          */
         Assert(parse->distinctClause == NIL);
         root->sort_pathkeys = make_pathkeys_for_sortclauses(root,
                                                             parse->sortClause,
                                                             tlist);
     }
     else
     {
         /* No set operations, do regular planning */
         PathTarget *sort_input_target;
         List       *sort_input_targets;
         List       *sort_input_targets_contain_srfs;
         bool        sort_input_target_parallel_safe;
         PathTarget *grouping_target;
         List       *grouping_targets;
         List       *grouping_targets_contain_srfs;
         bool        grouping_target_parallel_safe;
         PathTarget *scanjoin_target;
         List       *scanjoin_targets;
         List       *scanjoin_targets_contain_srfs;
         bool        scanjoin_target_parallel_safe;
         bool        scanjoin_target_same_exprs;
         bool        have_grouping;
         AggClauseCosts agg_costs;
         WindowFuncLists *wflists = NULL;
         List       *activeWindows = NIL;
         grouping_sets_data *gset_data = NULL;
         standard_qp_extra qp_extra;
 
         /* A recursive query should always have setOperations */
         Assert(!root->hasRecursion);
 
         /* Preprocess grouping sets and GROUP BY clause, if any */
         if (parse->groupingSets)
         {
             gset_data = preprocess_grouping_sets(root);
         }
         else
         {
             /* Preprocess regular GROUP BY clause, if any */
             if (parse->groupClause)
                 parse->groupClause = preprocess_groupclause(root, NIL);
         }
 
         /* Preprocess targetlist */
         tlist = preprocess_targetlist(root);
 
         /*
          * We are now done hacking up the query's targetlist.  Most of the
          * remaining planning work will be done with the PathTarget
          * representation of tlists, but save aside the full representation so
          * that we can transfer its decoration (resnames etc) to the topmost
          * tlist of the finished Plan.
          */
         root->processed_tlist = tlist;
 
         /*
          * Collect statistics about aggregates for estimating costs, and mark
          * all the aggregates with resolved aggtranstypes.  We must do this
          * before slicing and dicing the tlist into various pathtargets, else
          * some copies of the Aggref nodes might escape being marked with the
          * correct transtypes.
          *
          * Note: currently, we do not detect duplicate aggregates here.  This
          * may result in somewhat-overestimated cost, which is fine for our
          * purposes since all Paths will get charged the same.  But at some
          * point we might wish to do that detection in the planner, rather
          * than during executor startup.
          */
         MemSet(&agg_costs, 0, sizeof(AggClauseCosts));
         if (parse->hasAggs)
         {
             get_agg_clause_costs(root, (Node *) tlist, AGGSPLIT_SIMPLE,
                                  &agg_costs);
             get_agg_clause_costs(root, parse->havingQual, AGGSPLIT_SIMPLE,
                                  &agg_costs);
         }
 
         /*
          * Locate any window functions in the tlist.  (We don't need to look
          * anywhere else, since expressions used in ORDER BY will be in there
          * too.)  Note that they could all have been eliminated by constant
          * folding, in which case we don't need to do any more work.
          */
         if (parse->hasWindowFuncs)
         {
             wflists = find_window_functions((Node *) tlist,
                                             list_length(parse->windowClause));
             if (wflists->numWindowFuncs > 0)
                 activeWindows = select_active_windows(root, wflists);
             else
                 parse->hasWindowFuncs = false;
         }
 
         /*
          * Preprocess MIN/MAX aggregates, if any.  Note: be careful about
          * adding logic between here and the query_planner() call.  Anything
          * that is needed in MIN/MAX-optimizable cases will have to be
          * duplicated in planagg.c.
          */
         if (parse->hasAggs)
             preprocess_minmax_aggregates(root, tlist);
 
         /*
          * Figure out whether there's a hard limit on the number of rows that
          * query_planner's result subplan needs to return.  Even if we know a
          * hard limit overall, it doesn't apply if the query has any
          * grouping/aggregation operations, or SRFs in the tlist.
          */
         if (parse->groupClause ||
             parse->groupingSets ||
             parse->distinctClause ||
             parse->hasAggs ||
             parse->hasWindowFuncs ||
             parse->hasTargetSRFs ||
             root->hasHavingQual)
             root->limit_tuples = -1.0;
         else
             root->limit_tuples = limit_tuples;
 
         /* Set up data needed by standard_qp_callback */
         qp_extra.tlist = tlist;
         qp_extra.activeWindows = activeWindows;
         qp_extra.groupClause = (gset_data
                                 ? (gset_data->rollups ? linitial_node(RollupData, gset_data->rollups)->groupClause : NIL)
                                 : parse->groupClause);
 
         /*
          * Generate the best unsorted and presorted paths for the scan/join
          * portion of this Query, ie the processing represented by the
          * FROM/WHERE clauses.  (Note there may not be any presorted paths.)
          * We also generate (in standard_qp_callback) pathkey representations
          * of the query's sort clause, distinct clause, etc.
          */
         current_rel = query_planner(root, tlist,
                                     standard_qp_callback, &qp_extra);
 
         /*
          * Convert the query's result tlist into PathTarget format.
          *
          * Note: it's desirable to not do this till after query_planner(),
          * because the target width estimates can use per-Var width numbers
          * that were obtained within query_planner().
          */
         final_target = create_pathtarget(root, tlist);
         final_target_parallel_safe =
             is_parallel_safe(root, (Node *) final_target->exprs);
 
         /*
          * If ORDER BY was given, consider whether we should use a post-sort
          * projection, and compute the adjusted target for preceding steps if
          * so.
          */
         if (parse->sortClause)
         {
             sort_input_target = make_sort_input_target(root,
                                                        final_target,
                                                        &have_postponed_srfs);
             sort_input_target_parallel_safe =
                 is_parallel_safe(root, (Node *) sort_input_target->exprs);
         }
         else
         {
             sort_input_target = final_target;
             sort_input_target_parallel_safe = final_target_parallel_safe;
         }
 
         /*
          * If we have window functions to deal with, the output from any
          * grouping step needs to be what the window functions want;
          * otherwise, it should be sort_input_target.
          */
         if (activeWindows)
         {
             grouping_target = make_window_input_target(root,
                                                        final_target,
                                                        activeWindows);
             grouping_target_parallel_safe =
                 is_parallel_safe(root, (Node *) grouping_target->exprs);
         }
         else
         {
             grouping_target = sort_input_target;
             grouping_target_parallel_safe = sort_input_target_parallel_safe;
         }
 
         /*
          * If we have grouping or aggregation to do, the topmost scan/join
          * plan node must emit what the grouping step wants; otherwise, it
          * should emit grouping_target.
          */
         have_grouping = (parse->groupClause || parse->groupingSets ||
                          parse->hasAggs || root->hasHavingQual);
         if (have_grouping)
         {
             scanjoin_target = make_group_input_target(root, final_target);
             scanjoin_target_parallel_safe =
                 is_parallel_safe(root, (Node *) grouping_target->exprs);
         }
         else
         {
             scanjoin_target = grouping_target;
             scanjoin_target_parallel_safe = grouping_target_parallel_safe;
         }
 
         /*
          * If there are any SRFs in the targetlist, we must separate each of
          * these PathTargets into SRF-computing and SRF-free targets.  Replace
          * each of the named targets with a SRF-free version, and remember the
          * list of additional projection steps we need to add afterwards.
          */
         if (parse->hasTargetSRFs)
         {
             /* final_target doesn't recompute any SRFs in sort_input_target */
             split_pathtarget_at_srfs(root, final_target, sort_input_target,
                                      &final_targets,
                                      &final_targets_contain_srfs);
             final_target = linitial_node(PathTarget, final_targets);
             Assert(!linitial_int(final_targets_contain_srfs));
             /* likewise for sort_input_target vs. grouping_target */
             split_pathtarget_at_srfs(root, sort_input_target, grouping_target,
                                      &sort_input_targets,
                                      &sort_input_targets_contain_srfs);
             sort_input_target = linitial_node(PathTarget, sort_input_targets);
             Assert(!linitial_int(sort_input_targets_contain_srfs));
             /* likewise for grouping_target vs. scanjoin_target */
             split_pathtarget_at_srfs(root, grouping_target, scanjoin_target,
                                      &grouping_targets,
                                      &grouping_targets_contain_srfs);
             grouping_target = linitial_node(PathTarget, grouping_targets);
             Assert(!linitial_int(grouping_targets_contain_srfs));
             /* scanjoin_target will not have any SRFs precomputed for it */
             split_pathtarget_at_srfs(root, scanjoin_target, NULL,
                                      &scanjoin_targets,
                                      &scanjoin_targets_contain_srfs);
             scanjoin_target = linitial_node(PathTarget, scanjoin_targets);
             Assert(!linitial_int(scanjoin_targets_contain_srfs));
         }
         else
         {
             /* initialize lists; for most of these, dummy values are OK */
             final_targets = final_targets_contain_srfs = NIL;
             sort_input_targets = sort_input_targets_contain_srfs = NIL;
             grouping_targets = grouping_targets_contain_srfs = NIL;
             scanjoin_targets = list_make1(scanjoin_target);
             scanjoin_targets_contain_srfs = NIL;
         }
 
         /* Apply scan/join target. */
         scanjoin_target_same_exprs = list_length(scanjoin_targets) == 1
             && equal(scanjoin_target->exprs, current_rel->reltarget->exprs);
         apply_scanjoin_target_to_paths(root, current_rel, scanjoin_targets,
                                        scanjoin_targets_contain_srfs,
                                        scanjoin_target_parallel_safe,
                                        scanjoin_target_same_exprs);
 
         /*
          * Save the various upper-rel PathTargets we just computed into
          * root->upper_targets[].  The core code doesn't use this, but it
          * provides a convenient place for extensions to get at the info.  For
          * consistency, we save all the intermediate targets, even though some
          * of the corresponding upperrels might not be needed for this query.
          */
         root->upper_targets[UPPERREL_FINAL] = final_target;
         root->upper_targets[UPPERREL_WINDOW] = sort_input_target;
         root->upper_targets[UPPERREL_GROUP_AGG] = grouping_target;
 
         /*
          * If we have grouping and/or aggregation, consider ways to implement
          * that.  We build a new upperrel representing the output of this
          * phase.
          */
         if (have_grouping)
         {
             current_rel = create_grouping_paths(root,
                                                 current_rel,
                                                 grouping_target,
                                                 grouping_target_parallel_safe,
                                                 &agg_costs,
                                                 gset_data);
             /* Fix things up if grouping_target contains SRFs */
             if (parse->hasTargetSRFs)
                 adjust_paths_for_srfs(root, current_rel,
                                       grouping_targets,
                                       grouping_targets_contain_srfs);
         }
 
         /*
          * If we have window functions, consider ways to implement those.  We
          * build a new upperrel representing the output of this phase.
          */
         if (activeWindows)
         {
             current_rel = create_window_paths(root,
                                               current_rel,
                                               grouping_target,
                                               sort_input_target,
                                               sort_input_target_parallel_safe,
                                               tlist,
                                               wflists,
                                               activeWindows);
             /* Fix things up if sort_input_target contains SRFs */
             if (parse->hasTargetSRFs)
                 adjust_paths_for_srfs(root, current_rel,
                                       sort_input_targets,
                                       sort_input_targets_contain_srfs);
         }
 
         /*
          * If there is a DISTINCT clause, consider ways to implement that. We
          * build a new upperrel representing the output of this phase.
          */
         if (parse->distinctClause)
         {
             current_rel = create_distinct_paths(root,
                                                 current_rel);
         }
     }                           /* end of if (setOperations) */
 
     /*
      * If ORDER BY was given, consider ways to implement that, and generate a
      * new upperrel containing only paths that emit the correct ordering and
      * project the correct final_target.  We can apply the original
      * limit_tuples limit in sort costing here, but only if there are no
      * postponed SRFs.
      */
     if (parse->sortClause)
     {
         current_rel = create_ordered_paths(root,
                                            current_rel,
                                            final_target,
                                            final_target_parallel_safe,
                                            have_postponed_srfs ? -1.0 :
                                            limit_tuples);
         /* Fix things up if final_target contains SRFs */
         if (parse->hasTargetSRFs)
             adjust_paths_for_srfs(root, current_rel,
                                   final_targets,
                                   final_targets_contain_srfs);
     }
 
     /*
      * Now we are prepared to build the final-output upperrel.
      */
     final_rel = fetch_upper_rel(root, UPPERREL_FINAL, NULL);
 
     /*
      * If the input rel is marked consider_parallel and there's nothing that's
      * not parallel-safe in the LIMIT clause, then the final_rel can be marked
      * consider_parallel as well.  Note that if the query has rowMarks or is
      * not a SELECT, consider_parallel will be false for every relation in the
      * query.
      */
     if (current_rel->consider_parallel &&
         is_parallel_safe(root, parse->limitOffset) &&
         is_parallel_safe(root, parse->limitCount))
         final_rel->consider_parallel = true;
 
     /*
      * If the current_rel belongs to a single FDW, so does the final_rel.
      */
     final_rel->serverid = current_rel->serverid;
     final_rel->userid = current_rel->userid;
     final_rel->useridiscurrent = current_rel->useridiscurrent;
     final_rel->fdwroutine = current_rel->fdwroutine;
 
     /*
      * Generate paths for the final_rel.  Insert all surviving paths, with
      * LockRows, Limit, and/or ModifyTable steps added if needed.
      */
     foreach(lc, current_rel->pathlist)
     {
         Path       *path = (Path *) lfirst(lc);
 
         /*
          * If there is a FOR [KEY] UPDATE/SHARE clause, add the LockRows node.
          * (Note: we intentionally test parse->rowMarks not root->rowMarks
          * here.  If there are only non-locking rowmarks, they should be
          * handled by the ModifyTable node instead.  However, root->rowMarks
          * is what goes into the LockRows node.)
          */
         if (parse->rowMarks)
         {
             path = (Path *) create_lockrows_path(root, final_rel, path,
                                                  root->rowMarks,
                                                  SS_assign_special_param(root));
         }
 
         /*
          * If there is a LIMIT/OFFSET clause, add the LIMIT node.
          */
         if (limit_needed(parse))
         {
             path = (Path *) create_limit_path(root, final_rel, path,
                                               parse->limitOffset,
                                               parse->limitCount,
                                               offset_est, count_est);
         }
 
         /*
          * If this is an INSERT/UPDATE/DELETE, and we're not being called from
          * inheritance_planner, add the ModifyTable node.
          */
         if (parse->commandType != CMD_SELECT && !inheritance_update)
         {
             List       *withCheckOptionLists;
             List       *returningLists;
             List       *rowMarks;
 
             /*
              * Set up the WITH CHECK OPTION and RETURNING lists-of-lists, if
              * needed.
              */
             if (parse->withCheckOptions)
                 withCheckOptionLists = list_make1(parse->withCheckOptions);
             else
                 withCheckOptionLists = NIL;
 
             if (parse->returningList)
                 returningLists = list_make1(parse->returningList);
             else
                 returningLists = NIL;
 
             /*
              * If there was a FOR [KEY] UPDATE/SHARE clause, the LockRows node
              * will have dealt with fetching non-locked marked rows, else we
              * need to have ModifyTable do that.
              */
             if (parse->rowMarks)
                 rowMarks = NIL;
             else
                 rowMarks = root->rowMarks;
 
             path = (Path *)
                 create_modifytable_path(root, final_rel,
                                         parse->commandType,
                                         parse->canSetTag,
                                         parse->resultRelation,
                                         NIL,
                                         false,
                                         list_make1_int(parse->resultRelation),
                                         list_make1(path),
                                         list_make1(root),
                                         withCheckOptionLists,
                                         returningLists,
                                         rowMarks,
                                         parse->onConflict,
                                         SS_assign_special_param(root));
         }
 
         /* And shove it into final_rel */
         add_path(final_rel, path);
     }
 
     /*
      * Generate partial paths for final_rel, too, if outer query levels might
      * be able to make use of them.
      */
     if (final_rel->consider_parallel && root->query_level > 1 &&
         !limit_needed(parse))
     {
         Assert(!parse->rowMarks && parse->commandType == CMD_SELECT);
         foreach(lc, current_rel->partial_pathlist)
         {
             Path       *partial_path = (Path *) lfirst(lc);
 
             add_partial_path(final_rel, partial_path);
         }
     }
 
     /*
      * If there is an FDW that's responsible for all baserels of the query,
      * let it consider adding ForeignPaths.
      */
     if (final_rel->fdwroutine &&
         final_rel->fdwroutine->GetForeignUpperPaths)
         final_rel->fdwroutine->GetForeignUpperPaths(root, UPPERREL_FINAL,
                                                     current_rel, final_rel,
                                                     NULL);
 
     /* Let extensions possibly add some more paths */
     if (create_upper_paths_hook)
         (*create_upper_paths_hook) (root, UPPERREL_FINAL,
                                     current_rel, final_rel, NULL);
 
     /* Note: currently, we leave it to callers to do set_cheapest() */
 }

 /*
  * query_planner
  *    Generate a path (that is, a simplified plan) for a basic query,
  *    which may involve joins but not any fancier features.
  *
  * Since query_planner does not handle the toplevel processing (grouping,
  * sorting, etc) it cannot select the best path by itself.  Instead, it
  * returns the RelOptInfo for the top level of joining, and the caller
  * (grouping_planner) can choose among the surviving paths for the rel.
  *
  * root describes the query to plan
  * tlist is the target list the query should produce
  *      (this is NOT necessarily root->parse->targetList!)
  * qp_callback is a function to compute query_pathkeys once it's safe to do so
  * qp_extra is optional extra data to pass to qp_callback
  *
  * Note: the PlannerInfo node also includes a query_pathkeys field, which
  * tells query_planner the sort order that is desired in the final output
  * plan.  This value is *not* available at call time, but is computed by
  * qp_callback once we have completed merging the query's equivalence classes.
  * (We cannot construct canonical pathkeys until that's done.)
  */
 RelOptInfo *
 query_planner(PlannerInfo *root, List *tlist,
               query_pathkeys_callback qp_callback, void *qp_extra)
 {
     Query      *parse = root->parse;
     List       *joinlist;
     RelOptInfo *final_rel;
     Index       rti;
     double      total_pages;
 
     /*
      * If the query has an empty join tree, then it's something easy like
      * "SELECT 2+2;" or "INSERT ... VALUES()".  Fall through quickly.
      */
     if (parse->jointree->fromlist == NIL)
     {
         /* We need a dummy joinrel to describe the empty set of baserels */
         final_rel = build_empty_join_rel(root);
 
         /*
          * If query allows parallelism in general, check whether the quals are
          * parallel-restricted.  (We need not check final_rel->reltarget
          * because it's empty at this point.  Anything parallel-restricted in
          * the query tlist will be dealt with later.)
          */
         if (root->glob->parallelModeOK)
             final_rel->consider_parallel =
                 is_parallel_safe(root, parse->jointree->quals);
 
         /* The only path for it is a trivial Result path */
         add_path(final_rel, (Path *)
                  create_result_path(root, final_rel,
                                     final_rel->reltarget,
                                     (List *) parse->jointree->quals));
 
         /* Select cheapest path (pretty easy in this case...) */
         set_cheapest(final_rel);
 
         /*
          * We still are required to call qp_callback, in case it's something
          * like "SELECT 2+2 ORDER BY 1".
          */
         root->canon_pathkeys = NIL;
         (*qp_callback) (root, qp_extra);
 
         return final_rel;
  }

   /*
  * create_modifytable_path
  *    Creates a pathnode that represents performing INSERT/UPDATE/DELETE mods
  *
  * 'rel' is the parent relation associated with the result
  * 'operation' is the operation type
  * 'canSetTag' is true if we set the command tag/es_processed
  * 'nominalRelation' is the parent RT index for use of EXPLAIN
  * 'partitioned_rels' is an integer list of RT indexes of non-leaf tables in
  *      the partition tree, if this is an UPDATE/DELETE to a partitioned table.
  *      Otherwise NIL.
  * 'partColsUpdated' is true if any partitioning columns are being updated,
  *      either from the target relation or a descendent partitioned table.
  * 'resultRelations' is an integer list of actual RT indexes of target rel(s)
  * 'subpaths' is a list of Path(s) producing source data (one per rel)
  * 'subroots' is a list of PlannerInfo structs (one per rel)
  * 'withCheckOptionLists' is a list of WCO lists (one per rel)
  * 'returningLists' is a list of RETURNING tlists (one per rel)
  * 'rowMarks' is a list of PlanRowMarks (non-locking only)
  * 'onconflict' is the ON CONFLICT clause, or NULL
  * 'epqParam' is the ID of Param for EvalPlanQual re-eval
  */
 ModifyTablePath *
 create_modifytable_path(PlannerInfo *root, RelOptInfo *rel,
                         CmdType operation, bool canSetTag,
                         Index nominalRelation, List *partitioned_rels,
                         bool partColsUpdated,
                         List *resultRelations, List *subpaths,
                         List *subroots,
                         List *withCheckOptionLists, List *returningLists,
                         List *rowMarks, OnConflictExpr *onconflict,
                         int epqParam)
 {
     ModifyTablePath *pathnode = makeNode(ModifyTablePath);
     double      total_size;
     ListCell   *lc;
 
     Assert(list_length(resultRelations) == list_length(subpaths));
     Assert(list_length(resultRelations) == list_length(subroots));
     Assert(withCheckOptionLists == NIL ||
            list_length(resultRelations) == list_length(withCheckOptionLists));
     Assert(returningLists == NIL ||
            list_length(resultRelations) == list_length(returningLists));
 
     pathnode->path.pathtype = T_ModifyTable;
     pathnode->path.parent = rel;
     /* pathtarget is not interesting, just make it minimally valid */
     pathnode->path.pathtarget = rel->reltarget;
     /* For now, assume we are above any joins, so no parameterization */
     pathnode->path.param_info = NULL;
     pathnode->path.parallel_aware = false;
     pathnode->path.parallel_safe = false;
     pathnode->path.parallel_workers = 0;
     pathnode->path.pathkeys = NIL;
 
     /*
      * Compute cost & rowcount as sum of subpath costs & rowcounts.
      *
      * Currently, we don't charge anything extra for the actual table
      * modification work, nor for the WITH CHECK OPTIONS or RETURNING
      * expressions if any.  It would only be window dressing, since
      * ModifyTable is always a top-level node and there is no way for the
      * costs to change any higher-level planning choices.  But we might want
      * to make it look better sometime.
      */
     pathnode->path.startup_cost = 0;
     pathnode->path.total_cost = 0;
     pathnode->path.rows = 0;
     total_size = 0;
     foreach(lc, subpaths)
     {
         Path       *subpath = (Path *) lfirst(lc);
 
         if (lc == list_head(subpaths))  /* first node? */
             pathnode->path.startup_cost = subpath->startup_cost;
         pathnode->path.total_cost += subpath->total_cost;
         pathnode->path.rows += subpath->rows;
         total_size += subpath->pathtarget->width * subpath->rows;
     }
 
     /*
      * Set width to the average width of the subpath outputs.  XXX this is
      * totally wrong: we should report zero if no RETURNING, else an average
      * of the RETURNING tlist widths.  But it's what happened historically,
      * and improving it is a task for another day.
      */
     if (pathnode->path.rows > 0)
         total_size /= pathnode->path.rows;
     pathnode->path.pathtarget->width = rint(total_size);
 
     pathnode->operation = operation;
     pathnode->canSetTag = canSetTag;
     pathnode->nominalRelation = nominalRelation;
     pathnode->partitioned_rels = list_copy(partitioned_rels);
     pathnode->partColsUpdated = partColsUpdated;
     pathnode->resultRelations = resultRelations;
     pathnode->subpaths = subpaths;
     pathnode->subroots = subroots;
     pathnode->withCheckOptionLists = withCheckOptionLists;
     pathnode->returningLists = returningLists;
     pathnode->rowMarks = rowMarks;
     pathnode->onconflict = onconflict;
     pathnode->epqParam = epqParam;
 
     return pathnode;
 }
 

2、subquery_planner

 /*--------------------
  * subquery_planner
  *    Invokes the planner on a subquery.  We recurse to here for each
  *    sub-SELECT found in the query tree.
  *
  * glob is the global state for the current planner run.
  * parse is the querytree produced by the parser & rewriter.
  * parent_root is the immediate parent Query's info (NULL at the top level).
  * hasRecursion is true if this is a recursive WITH query.
  * tuple_fraction is the fraction of tuples we expect will be retrieved.
  * tuple_fraction is interpreted as explained for grouping_planner, below.
  *
  * Basically, this routine does the stuff that should only be done once
  * per Query object.  It then calls grouping_planner.  At one time,
  * grouping_planner could be invoked recursively on the same Query object;
  * that's not currently true, but we keep the separation between the two
  * routines anyway, in case we need it again someday.
  *
  * subquery_planner will be called recursively to handle sub-Query nodes
  * found within the query's expressions and rangetable.
  *
  * Returns the PlannerInfo struct ("root") that contains all data generated
  * while planning the subquery.  In particular, the Path(s) attached to
  * the (UPPERREL_FINAL, NULL) upperrel represent our conclusions about the
  * cheapest way(s) to implement the query.  The top level will select the
  * best Path and pass it through createplan.c to produce a finished Plan.
  *--------------------
  */
/*
輸入:
  glob-PlannerGlobal
  parse-Query結構體指標
  parent_root-父PlannerInfo Root節點
  hasRecursion-是否遞迴?
  tuple_fraction-掃描Tuple比例
輸出:
  PlannerInfo指標
*/
 PlannerInfo *
 subquery_planner(PlannerGlobal *glob, Query *parse,
                  PlannerInfo *parent_root,
                  bool hasRecursion, double tuple_fraction)
 {
     PlannerInfo *root;//返回值
     List       *newWithCheckOptions;//
     List       *newHaving;//Having子句
     bool        hasOuterJoins;//是否存在Outer Join?
     RelOptInfo *final_rel;//
     ListCell   *l;//臨時變數
 
     /* Create a PlannerInfo data structure for this subquery */
     root = makeNode(PlannerInfo);//構造返回值
     root->parse = parse;
     root->glob = glob;
     root->query_level = parent_root ? parent_root->query_level + 1 : 1;
     root->parent_root = parent_root;
     root->plan_params = NIL;
     root->outer_params = NULL;
     root->planner_cxt = CurrentMemoryContext;
     root->init_plans = NIL;
     root->cte_plan_ids = NIL;
     root->multiexpr_params = NIL;
     root->eq_classes = NIL;
     root->append_rel_list = NIL;
     root->rowMarks = NIL;
     memset(root->upper_rels, 0, sizeof(root->upper_rels));
     memset(root->upper_targets, 0, sizeof(root->upper_targets));
     root->processed_tlist = NIL;
     root->grouping_map = NULL;
     root->minmax_aggs = NIL;
     root->qual_security_level = 0;
     root->inhTargetKind = INHKIND_NONE;
     root->hasRecursion = hasRecursion;
     if (hasRecursion)
         root->wt_param_id = SS_assign_special_param(root);
     else
         root->wt_param_id = -1;
     root->non_recursive_path = NULL;
     root->partColsUpdated = false;
 
     /*
      * If there is a WITH list, process each WITH query and build an initplan
      * SubPlan structure for it.
      */
     if (parse->cteList)
         SS_process_ctes(root);//With 語句
 
     /*
      * Look for ANY and EXISTS SubLinks in WHERE and JOIN/ON clauses, and try
      * to transform them into joins.  Note that this step does not descend
      * into subqueries; if we pull up any subqueries below, their SubLinks are
      * processed just before pulling them up.
      */
     if (parse->hasSubLinks)
         pull_up_sublinks(root); //轉換ANY/EXISTS為JOIN
 
     /*
      * Scan the rangetable for set-returning functions, and inline them if
      * possible (producing subqueries that might get pulled up next).
      * Recursion issues here are handled in the same way as for SubLinks.
      */
     inline_set_returning_functions(root);
 
     /*
      * Check to see if any subqueries in the jointree can be merged into this
      * query.
      */
     pull_up_subqueries(root);//
 
     /*
      * If this is a simple UNION ALL query, flatten it into an appendrel. We
      * do this now because it requires applying pull_up_subqueries to the leaf
      * queries of the UNION ALL, which weren't touched above because they
      * weren't referenced by the jointree (they will be after we do this).
      */
     if (parse->setOperations)
         flatten_simple_union_all(root);
 
     /*
      * Detect whether any rangetable entries are RTE_JOIN kind; if not, we can
      * avoid the expense of doing flatten_join_alias_vars().  Also check for
      * outer joins --- if none, we can skip reduce_outer_joins().  And check
      * for LATERAL RTEs, too.  This must be done after we have done
      * pull_up_subqueries(), of course.
      */
     root->hasJoinRTEs = false;
     root->hasLateralRTEs = false;
     hasOuterJoins = false;
     foreach(l, parse->rtable)
     {
         RangeTblEntry *rte = lfirst_node(RangeTblEntry, l);
 
         if (rte->rtekind == RTE_JOIN)
         {
             root->hasJoinRTEs = true;
             if (IS_OUTER_JOIN(rte->jointype))
                 hasOuterJoins = true;
         }
         if (rte->lateral)
             root->hasLateralRTEs = true;
     }
 
     /*
      * Preprocess RowMark information.  We need to do this after subquery
      * pullup (so that all non-inherited RTEs are present) and before
      * inheritance expansion (so that the info is available for
      * expand_inherited_tables to examine and modify).
      */
     preprocess_rowmarks(root);
 
     /*
      * Expand any rangetable entries that are inheritance sets into "append
      * relations".  This can add entries to the rangetable, but they must be
      * plain base relations not joins, so it's OK (and marginally more
      * efficient) to do it after checking for join RTEs.  We must do it after
      * pulling up subqueries, else we'd fail to handle inherited tables in
      * subqueries.
      */
     expand_inherited_tables(root);
 
     /*
      * Set hasHavingQual to remember if HAVING clause is present.  Needed
      * because preprocess_expression will reduce a constant-true condition to
      * an empty qual list ... but "HAVING TRUE" is not a semantic no-op.
      */
     root->hasHavingQual = (parse->havingQual != NULL);
 
     /* Clear this flag; might get set in distribute_qual_to_rels */
     root->hasPseudoConstantQuals = false;
 
     /*
      * Do expression preprocessing on targetlist and quals, as well as other
      * random expressions in the querytree.  Note that we do not need to
      * handle sort/group expressions explicitly, because they are actually
      * part of the targetlist.
      */
     parse->targetList = (List *)
         preprocess_expression(root, (Node *) parse->targetList,
                               EXPRKIND_TARGET);
 
     /* Constant-folding might have removed all set-returning functions */
     if (parse->hasTargetSRFs)
         parse->hasTargetSRFs = expression_returns_set((Node *) parse->targetList);
 
     newWithCheckOptions = NIL;
     foreach(l, parse->withCheckOptions)
     {
         WithCheckOption *wco = lfirst_node(WithCheckOption, l);
 
         wco->qual = preprocess_expression(root, wco->qual,
                                           EXPRKIND_QUAL);
         if (wco->qual != NULL)
             newWithCheckOptions = lappend(newWithCheckOptions, wco);
     }
     parse->withCheckOptions = newWithCheckOptions;
 
     parse->returningList = (List *)
         preprocess_expression(root, (Node *) parse->returningList,
                               EXPRKIND_TARGET);
 
     preprocess_qual_conditions(root, (Node *) parse->jointree);
 
     parse->havingQual = preprocess_expression(root, parse->havingQual,
                                               EXPRKIND_QUAL);
 
     foreach(l, parse->windowClause)
     {
         WindowClause *wc = lfirst_node(WindowClause, l);
 
         /* partitionClause/orderClause are sort/group expressions */
         wc->startOffset = preprocess_expression(root, wc->startOffset,
                                                 EXPRKIND_LIMIT);
         wc->endOffset = preprocess_expression(root, wc->endOffset,
                                               EXPRKIND_LIMIT);
     }
 
     parse->limitOffset = preprocess_expression(root, parse->limitOffset,
                                                EXPRKIND_LIMIT);
     parse->limitCount = preprocess_expression(root, parse->limitCount,
                                               EXPRKIND_LIMIT);
 
     if (parse->onConflict)
     {
         parse->onConflict->arbiterElems = (List *)
             preprocess_expression(root,
                                   (Node *) parse->onConflict->arbiterElems,
                                   EXPRKIND_ARBITER_ELEM);
         parse->onConflict->arbiterWhere =
             preprocess_expression(root,
                                   parse->onConflict->arbiterWhere,
                                   EXPRKIND_QUAL);
         parse->onConflict->onConflictSet = (List *)
             preprocess_expression(root,
                                   (Node *) parse->onConflict->onConflictSet,
                                   EXPRKIND_TARGET);
         parse->onConflict->onConflictWhere =
             preprocess_expression(root,
                                   parse->onConflict->onConflictWhere,
                                   EXPRKIND_QUAL);
         /* exclRelTlist contains only Vars, so no preprocessing needed */
     }
 
     root->append_rel_list = (List *)
         preprocess_expression(root, (Node *) root->append_rel_list,
                               EXPRKIND_APPINFO);
 
     /* Also need to preprocess expressions within RTEs */
     foreach(l, parse->rtable)
     {
         RangeTblEntry *rte = lfirst_node(RangeTblEntry, l);
         int         kind;
         ListCell   *lcsq;
 
         if (rte->rtekind == RTE_RELATION)
         {
             if (rte->tablesample)
                 rte->tablesample = (TableSampleClause *)
                     preprocess_expression(root,
                                           (Node *) rte->tablesample,
                                           EXPRKIND_TABLESAMPLE);
         }
         else if (rte->rtekind == RTE_SUBQUERY)
         {
             /*
              * We don't want to do all preprocessing yet on the subquery's
              * expressions, since that will happen when we plan it.  But if it
              * contains any join aliases of our level, those have to get
              * expanded now, because planning of the subquery won't do it.
              * That's only possible if the subquery is LATERAL.
              */
             if (rte->lateral && root->hasJoinRTEs)
                 rte->subquery = (Query *)
                     flatten_join_alias_vars(root, (Node *) rte->subquery);
         }
         else if (rte->rtekind == RTE_FUNCTION)
         {
             /* Preprocess the function expression(s) fully */
             kind = rte->lateral ? EXPRKIND_RTFUNC_LATERAL : EXPRKIND_RTFUNC;
             rte->functions = (List *)
                 preprocess_expression(root, (Node *) rte->functions, kind);
         }
         else if (rte->rtekind == RTE_TABLEFUNC)
         {
             /* Preprocess the function expression(s) fully */
             kind = rte->lateral ? EXPRKIND_TABLEFUNC_LATERAL : EXPRKIND_TABLEFUNC;
             rte->tablefunc = (TableFunc *)
                 preprocess_expression(root, (Node *) rte->tablefunc, kind);
         }
         else if (rte->rtekind == RTE_VALUES)
         {
             /* Preprocess the values lists fully */
             kind = rte->lateral ? EXPRKIND_VALUES_LATERAL : EXPRKIND_VALUES;
             rte->values_lists = (List *)
                 preprocess_expression(root, (Node *) rte->values_lists, kind);
         }
 
         /*
          * Process each element of the securityQuals list as if it were a
          * separate qual expression (as indeed it is).  We need to do it this
          * way to get proper canonicalization of AND/OR structure.  Note that
          * this converts each element into an implicit-AND sublist.
          */
         foreach(lcsq, rte->securityQuals)
         {
             lfirst(lcsq) = preprocess_expression(root,
                                                  (Node *) lfirst(lcsq),
                                                  EXPRKIND_QUAL);
         }
     }
 
     /*
      * Now that we are done preprocessing expressions, and in particular done
      * flattening join alias variables, get rid of the joinaliasvars lists.
      * They no longer match what expressions in the rest of the tree look
      * like, because we have not preprocessed expressions in those lists (and
      * do not want to; for example, expanding a SubLink there would result in
      * a useless unreferenced subplan).  Leaving them in place simply creates
      * a hazard for later scans of the tree.  We could try to prevent that by
      * using QTW_IGNORE_JOINALIASES in every tree scan done after this point,
      * but that doesn't sound very reliable.
      */
     if (root->hasJoinRTEs)
     {
         foreach(l, parse->rtable)
         {
             RangeTblEntry *rte = lfirst_node(RangeTblEntry, l);
 
             rte->joinaliasvars = NIL;
         }
     }
 
     /*
      * In some cases we may want to transfer a HAVING clause into WHERE. We
      * cannot do so if the HAVING clause contains aggregates (obviously) or
      * volatile functions (since a HAVING clause is supposed to be executed
      * only once per group).  We also can't do this if there are any nonempty
      * grouping sets; moving such a clause into WHERE would potentially change
      * the results, if any referenced column isn't present in all the grouping
      * sets.  (If there are only empty grouping sets, then the HAVING clause
      * must be degenerate as discussed below.)
      *
      * Also, it may be that the clause is so expensive to execute that we're
      * better off doing it only once per group, despite the loss of
      * selectivity.  This is hard to estimate short of doing the entire
      * planning process twice, so we use a heuristic: clauses containing
      * subplans are left in HAVING.  Otherwise, we move or copy the HAVING
      * clause into WHERE, in hopes of eliminating tuples before aggregation
      * instead of after.
      *
      * If the query has explicit grouping then we can simply move such a
      * clause into WHERE; any group that fails the clause will not be in the
      * output because none of its tuples will reach the grouping or
      * aggregation stage.  Otherwise we must have a degenerate (variable-free)
      * HAVING clause, which we put in WHERE so that query_planner() can use it
      * in a gating Result node, but also keep in HAVING to ensure that we
      * don't emit a bogus aggregated row. (This could be done better, but it
      * seems not worth optimizing.)
      *
      * Note that both havingQual and parse->jointree->quals are in
      * implicitly-ANDed-list form at this point, even though they are declared
      * as Node *.
      */
     newHaving = NIL;
     foreach(l, (List *) parse->havingQual)
     {
         Node       *havingclause = (Node *) lfirst(l);
 
         if ((parse->groupClause && parse->groupingSets) ||
             contain_agg_clause(havingclause) ||
             contain_volatile_functions(havingclause) ||
             contain_subplans(havingclause))
         {
             /* keep it in HAVING */
             newHaving = lappend(newHaving, havingclause);
         }
         else if (parse->groupClause && !parse->groupingSets)
         {
             /* move it to WHERE */
             parse->jointree->quals = (Node *)
                 lappend((List *) parse->jointree->quals, havingclause);
         }
         else
         {
             /* put a copy in WHERE, keep it in HAVING */
             parse->jointree->quals = (Node *)
                 lappend((List *) parse->jointree->quals,
                         copyObject(havingclause));
             newHaving = lappend(newHaving, havingclause);
         }
     }
     parse->havingQual = (Node *) newHaving;
 
     /* Remove any redundant GROUP BY columns */
     remove_useless_groupby_columns(root);
 
     /*
      * If we have any outer joins, try to reduce them to plain inner joins.
      * This step is most easily done after we've done expression
      * preprocessing.
      */
     if (hasOuterJoins)
         reduce_outer_joins(root);
 
     /*
      * Do the main planning.  If we have an inherited target relation, that
      * needs special processing, else go straight to grouping_planner.
      */
     if (parse->resultRelation &&
         rt_fetch(parse->resultRelation, parse->rtable)->inh)
         inheritance_planner(root);
     else
         grouping_planner(root, false, tuple_fraction);
 
     /*
      * Capture the set of outer-level param IDs we have access to, for use in
      * extParam/allParam calculations later.
      */
     SS_identify_outer_params(root);
 
     /*
      * If any initPlans were created in this query level, adjust the surviving
      * Paths' costs and parallel-safety flags to account for them.  The
      * initPlans won't actually get attached to the plan tree till
      * create_plan() runs, but we must include their effects now.
      */
     final_rel = fetch_upper_rel(root, UPPERREL_FINAL, NULL);
     SS_charge_for_initplans(root, final_rel);
 
     /*
      * Make sure we've identified the cheapest Path for the final rel.  (By
      * doing this here not in grouping_planner, we include initPlan costs in
      * the decision, though it's unlikely that will change anything.)
      */
     set_cheapest(final_rel);
 
     return root;
 }
 

3.create_plan

 /*
  * create_plan
  *    Creates the access plan for a query by recursively processing the
  *    desired tree of pathnodes, starting at the node 'best_path'.  For
  *    every pathnode found, we create a corresponding plan node containing
  *    appropriate id, target list, and qualification information.
  *
  *    The tlists and quals in the plan tree are still in planner format,
  *    ie, Vars still correspond to the parser's numbering.  This will be
  *    fixed later by setrefs.c.
  *
  *    best_path is the best access path
  *
  *    Returns a Plan tree.
  */
 Plan *
 create_plan(PlannerInfo *root, Path *best_path)
 {
     Plan       *plan;
 
     /* plan_params should not be in use in current query level */
     Assert(root->plan_params == NIL);
 
     /* Initialize this module's private workspace in PlannerInfo */
     root->curOuterRels = NULL;
     root->curOuterParams = NIL;
 
     /* Recursively process the path tree, demanding the correct tlist result */
     plan = create_plan_recurse(root, best_path, CP_EXACT_TLIST);
 
     /*
      * Make sure the topmost plan node's targetlist exposes the original
      * column names and other decorative info.  Targetlists generated within
      * the planner don't bother with that stuff, but we must have it on the
      * top-level tlist seen at execution time.  However, ModifyTable plan
      * nodes don't have a tlist matching the querytree targetlist.
      */
     if (!IsA(plan, ModifyTable))
         apply_tlist_labeling(plan->targetlist, root->processed_tlist);
 
     /*
      * Attach any initPlans created in this query level to the topmost plan
      * node.  (In principle the initplans could go in any plan node at or
      * above where they're referenced, but there seems no reason to put them
      * any lower than the topmost node for the query level.  Also, see
      * comments for SS_finalize_plan before you try to change this.)
      */
     SS_attach_initplans(root, plan);
 
     /* Check we successfully assigned all NestLoopParams to plan nodes */
     if (root->curOuterParams != NIL)
         elog(ERROR, "failed to assign all NestLoopParams to plan nodes");
 
     /*
      * Reset plan_params to ensure param IDs used for nestloop params are not
      * re-used later
      */
     root->plan_params = NIL;
 
     return plan;
 }

/*
  * create_plan_recurse
  *    Recursive guts of create_plan().
  */
 static Plan *
 create_plan_recurse(PlannerInfo *root, Path *best_path, int flags)
 {
     Plan       *plan;
 
     /* Guard against stack overflow due to overly complex plans */
     check_stack_depth();
 
     switch (best_path->pathtype)
     {
         case T_SeqScan:
         case T_SampleScan:
         case T_IndexScan:
         case T_IndexOnlyScan:
         case T_BitmapHeapScan:
         case T_TidScan:
         case T_SubqueryScan:
         case T_FunctionScan:
         case T_TableFuncScan:
         case T_ValuesScan:
         case T_CteScan:
         case T_WorkTableScan:
         case T_NamedTuplestoreScan:
         case T_ForeignScan:
         case T_CustomScan:
             plan = create_scan_plan(root, best_path, flags);
             break;
         case T_HashJoin:
         case T_MergeJoin:
         case T_NestLoop:
             plan = create_join_plan(root,
                                     (JoinPath *) best_path);
             break;
         case T_Append:
             plan = create_append_plan(root,
                                       (AppendPath *) best_path);
             break;
         case T_MergeAppend:
             plan = create_merge_append_plan(root,
                                             (MergeAppendPath *) best_path);
             break;
         case T_Result:
             if (IsA(best_path, ProjectionPath))
             {
                 plan = create_projection_plan(root,
                                               (ProjectionPath *) best_path,
                                               flags);
             }
             else if (IsA(best_path, MinMaxAggPath))
             {
                 plan = (Plan *) create_minmaxagg_plan(root,
                                                       (MinMaxAggPath *) best_path);
             }
             else
             {
                 Assert(IsA(best_path, ResultPath));
                 plan = (Plan *) create_result_plan(root,
                                                    (ResultPath *) best_path);
             }
             break;
         case T_ProjectSet:
             plan = (Plan *) create_project_set_plan(root,
                                                     (ProjectSetPath *) best_path);
             break;
         case T_Material:
             plan = (Plan *) create_material_plan(root,
                                                  (MaterialPath *) best_path,
                                                  flags);
             break;
         case T_Unique:
             if (IsA(best_path, UpperUniquePath))
             {
                 plan = (Plan *) create_upper_unique_plan(root,
                                                          (UpperUniquePath *) best_path,
                                                          flags);
             }
             else
             {
                 Assert(IsA(best_path, UniquePath));
                 plan = create_unique_plan(root,
                                           (UniquePath *) best_path,
                                           flags);
             }
             break;
         case T_Gather:
             plan = (Plan *) create_gather_plan(root,
                                                (GatherPath *) best_path);
             break;
         case T_Sort:
             plan = (Plan *) create_sort_plan(root,
                                              (SortPath *) best_path,
                                              flags);
             break;
         case T_Group:
             plan = (Plan *) create_group_plan(root,
                                               (GroupPath *) best_path);
             break;
         case T_Agg:
             if (IsA(best_path, GroupingSetsPath))
                 plan = create_groupingsets_plan(root,
                                                 (GroupingSetsPath *) best_path);
             else
             {
                 Assert(IsA(best_path, AggPath));
                 plan = (Plan *) create_agg_plan(root,
                                                 (AggPath *) best_path);
             }
             break;
         case T_WindowAgg:
             plan = (Plan *) create_windowagg_plan(root,
                                                   (WindowAggPath *) best_path);
             break;
         case T_SetOp:
             plan = (Plan *) create_setop_plan(root,
                                               (SetOpPath *) best_path,
                                               flags);
             break;
         case T_RecursiveUnion:
             plan = (Plan *) create_recursiveunion_plan(root,
                                                        (RecursiveUnionPath *) best_path);
             break;
         case T_LockRows:
             plan = (Plan *) create_lockrows_plan(root,
                                                  (LockRowsPath *) best_path,
                                                  flags);
             break;
         case T_ModifyTable:
             plan = (Plan *) create_modifytable_plan(root,
                                                     (ModifyTablePath *) best_path);
             break;
         case T_Limit:
             plan = (Plan *) create_limit_plan(root,
                                               (LimitPath *) best_path,
                                               flags);
             break;
         case T_GatherMerge:
             plan = (Plan *) create_gather_merge_plan(root,
                                                      (GatherMergePath *) best_path);
             break;
         default:
             elog(ERROR, "unrecognized node type: %d",
                  (int) best_path->pathtype);
             plan = NULL;        /* keep compiler quiet */
             break;
     }
 
     return plan;
 }

 /*
  * create_modifytable_plan
  *    Create a ModifyTable plan for 'best_path'.
  *
  *    Returns a Plan node.
  */
 static ModifyTable *
 create_modifytable_plan(PlannerInfo *root, ModifyTablePath *best_path)
 {
     ModifyTable *plan;
     List       *subplans = NIL;
     ListCell   *subpaths,
                *subroots;
 
     /* Build the plan for each input path */
     forboth(subpaths, best_path->subpaths,
             subroots, best_path->subroots)
     {
         Path       *subpath = (Path *) lfirst(subpaths);
         PlannerInfo *subroot = (PlannerInfo *) lfirst(subroots);
         Plan       *subplan;
 
         /*
          * In an inherited UPDATE/DELETE, reference the per-child modified
          * subroot while creating Plans from Paths for the child rel.  This is
          * a kluge, but otherwise it's too hard to ensure that Plan creation
          * functions (particularly in FDWs) don't depend on the contents of
          * "root" matching what they saw at Path creation time.  The main
          * downside is that creation functions for Plans that might appear
          * below a ModifyTable cannot expect to modify the contents of "root"
          * and have it "stick" for subsequent processing such as setrefs.c.
          * That's not great, but it seems better than the alternative.
          */
         subplan = create_plan_recurse(subroot, subpath, CP_EXACT_TLIST);
 
         /* Transfer resname/resjunk labeling, too, to keep executor happy */
         apply_tlist_labeling(subplan->targetlist, subroot->processed_tlist);
 
         subplans = lappend(subplans, subplan);
     }
 
     plan = make_modifytable(root,
                             best_path->operation,
                             best_path->canSetTag,
                             best_path->nominalRelation,
                             best_path->partitioned_rels,
                             best_path->partColsUpdated,
                             best_path->resultRelations,
                             subplans,
                             best_path->subroots,
                             best_path->withCheckOptionLists,
                             best_path->returningLists,
                             best_path->rowMarks,
                             best_path->onconflict,
                             best_path->epqParam);
 
     copy_generic_path_info(&plan->plan, &best_path->path);
 
     return plan;
 }

 /*
  * make_modifytable
  *    Build a ModifyTable plan node
  */
 static ModifyTable *
 make_modifytable(PlannerInfo *root,
                  CmdType operation, bool canSetTag,
                  Index nominalRelation, List *partitioned_rels,
                  bool partColsUpdated,
                  List *resultRelations, List *subplans, List *subroots,
                  List *withCheckOptionLists, List *returningLists,
                  List *rowMarks, OnConflictExpr *onconflict, int epqParam)
 {
     ModifyTable *node = makeNode(ModifyTable);
     List       *fdw_private_list;
     Bitmapset  *direct_modify_plans;
     ListCell   *lc;
     ListCell   *lc2;
     int         i;
 
     Assert(list_length(resultRelations) == list_length(subplans));
     Assert(list_length(resultRelations) == list_length(subroots));
     Assert(withCheckOptionLists == NIL ||
            list_length(resultRelations) == list_length(withCheckOptionLists));
     Assert(returningLists == NIL ||
            list_length(resultRelations) == list_length(returningLists));
 
     node->plan.lefttree = NULL;
     node->plan.righttree = NULL;
     node->plan.qual = NIL;
     /* setrefs.c will fill in the targetlist, if needed */
     node->plan.targetlist = NIL;
 
     node->operation = operation;
     node->canSetTag = canSetTag;
     node->nominalRelation = nominalRelation;
     node->partitioned_rels = flatten_partitioned_rels(partitioned_rels);
     node->partColsUpdated = partColsUpdated;
     node->resultRelations = resultRelations;
     node->resultRelIndex = -1;  /* will be set correctly in setrefs.c */
     node->rootResultRelIndex = -1;  /* will be set correctly in setrefs.c */
     node->plans = subplans;
     if (!onconflict)
     {
         node->onConflictAction = ONCONFLICT_NONE;
         node->onConflictSet = NIL;
         node->onConflictWhere = NULL;
         node->arbiterIndexes = NIL;
         node->exclRelRTI = 0;
         node->exclRelTlist = NIL;
     }
     else
     {
         node->onConflictAction = onconflict->action;
         node->onConflictSet = onconflict->onConflictSet;
         node->onConflictWhere = onconflict->onConflictWhere;
 
         /*
          * If a set of unique index inference elements was provided (an
          * INSERT...ON CONFLICT "inference specification"), then infer
          * appropriate unique indexes (or throw an error if none are
          * available).
          */
         node->arbiterIndexes = infer_arbiter_indexes(root);
 
         node->exclRelRTI = onconflict->exclRelIndex;
         node->exclRelTlist = onconflict->exclRelTlist;
     }
     node->withCheckOptionLists = withCheckOptionLists;
     node->returningLists = returningLists;
     node->rowMarks = rowMarks;
     node->epqParam = epqParam;
 
     /*
      * For each result relation that is a foreign table, allow the FDW to
      * construct private plan data, and accumulate it all into a list.
      */
     fdw_private_list = NIL;
     direct_modify_plans = NULL;
     i = 0;
     forboth(lc, resultRelations, lc2, subroots)
     {
         Index       rti = lfirst_int(lc);
         PlannerInfo *subroot = lfirst_node(PlannerInfo, lc2);
         FdwRoutine *fdwroutine;
         List       *fdw_private;
         bool        direct_modify;
 
         /*
          * If possible, we want to get the FdwRoutine from our RelOptInfo for
          * the table.  But sometimes we don't have a RelOptInfo and must get
          * it the hard way.  (In INSERT, the target relation is not scanned,
          * so it's not a baserel; and there are also corner cases for
          * updatable views where the target rel isn't a baserel.)
          */
         if (rti < subroot->simple_rel_array_size &&
             subroot->simple_rel_array[rti] != NULL)
         {
             RelOptInfo *resultRel = subroot->simple_rel_array[rti];
 
             fdwroutine = resultRel->fdwroutine;
         }
         else
         {
             RangeTblEntry *rte = planner_rt_fetch(rti, subroot);
 
             Assert(rte->rtekind == RTE_RELATION);
             if (rte->relkind == RELKIND_FOREIGN_TABLE)
                 fdwroutine = GetFdwRoutineByRelId(rte->relid);
             else
                 fdwroutine = NULL;
         }
 
         /*
          * Try to modify the foreign table directly if (1) the FDW provides
          * callback functions needed for that, (2) there are no row-level
          * triggers on the foreign table, and (3) there are no WITH CHECK
          * OPTIONs from parent views.
          */
         direct_modify = false;
         if (fdwroutine != NULL &&
             fdwroutine->PlanDirectModify != NULL &&
             fdwroutine->BeginDirectModify != NULL &&
             fdwroutine->IterateDirectModify != NULL &&
             fdwroutine->EndDirectModify != NULL &&
             withCheckOptionLists == NIL &&
             !has_row_triggers(subroot, rti, operation))
             direct_modify = fdwroutine->PlanDirectModify(subroot, node, rti, i);
         if (direct_modify)
             direct_modify_plans = bms_add_member(direct_modify_plans, i);
 
         if (!direct_modify &&
             fdwroutine != NULL &&
             fdwroutine->PlanForeignModify != NULL)
             fdw_private = fdwroutine->PlanForeignModify(subroot, node, rti, i);
         else
             fdw_private = NIL;
         fdw_private_list = lappend(fdw_private_list, fdw_private);
         i++;
     }
     node->fdwPrivLists = fdw_private_list;
     node->fdwDirectModifyPlans = direct_modify_plans;
 
     return node;
 }
 

三、跟蹤分析

插入測試資料:

testdb=# insert into t_insert values(1000,'I am test','I am test','I am test');
(掛起)

啟動gdb,跟蹤除錯:

standard_planner

[root@localhost ~]# gdb -p 1610
GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-100.el7
Copyright (C) 2013 Free Software Foundation, Inc.
...
#跟蹤進入subquery_planner(見後)
(gdb) n
409   final_rel = fetch_upper_rel(root, UPPERREL_FINAL, NULL);
(gdb) 
410   best_path = get_cheapest_fractional_path(final_rel, tuple_fraction);
#最優路徑,INSERT語句,Plan為T_ModifyTable
(gdb) p *best_path
$51 = {type = T_ModifyTablePath, pathtype = T_ModifyTable, parent = 0x21c40a0, pathtarget = 0x21c42b0, 
  param_info = 0x0, parallel_aware = false, parallel_safe = false, parallel_workers = 0, rows = 1, 
  startup_cost = 0, total_cost = 0.01, pathkeys = 0x0}
(gdb) 
412   top_plan = create_plan(root, best_path);
(gdb) step
create_plan (root=0x21c2cb0, best_path=0x219dd88) at createplan.c:323
323   root->curOuterRels = NULL;
(gdb) n
324   root->curOuterParams = NIL;
(gdb) 
327   plan = create_plan_recurse(root, best_path, CP_EXACT_TLIST);
(gdb) 
336   if (!IsA(plan, ModifyTable))
#plan可用於後續的執行
(gdb) p *plan
$53 = {type = T_ModifyTable, startup_cost = 0, total_cost = 0.01, plan_rows = 1, plan_width = 298, 
  parallel_aware = false, parallel_safe = false, plan_node_id = 0, targetlist = 0x0, qual = 0x0, 
  lefttree = 0x0, righttree = 0x0, initPlan = 0x0, extParam = 0x0, allParam = 0x0}

subquery_planner

[root@localhost ~]# gdb -p 1610
GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-100.el7
Copyright (C) 2013 Free Software Foundation, Inc.
...
(gdb) b subquery_planner
Breakpoint 1 at 0x76a0bb: file planner.c, line 606.
(gdb) c
Continuing.
...
Breakpoint 1, subquery_planner (glob=0x21c2c20, parse=0x219de98, parent_root=0x0, hasRecursion=false, 
    tuple_fraction=0) at planner.c:606
606     root = makeNode(PlannerInfo);
#輸入引數
#1,glob
(gdb) p *glob
$1 = {type = T_PlannerGlobal, boundParams = 0x0, subplans = 0x0, subroots = 0x0, rewindPlanIDs = 0x0, 
  finalrtable = 0x0, finalrowmarks = 0x0, resultRelations = 0x0, nonleafResultRelations = 0x0, 
  rootResultRelations = 0x0, relationOids = 0x0, invalItems = 0x0, paramExecTypes = 0x0, lastPHId = 0, 
  lastRowMarkId = 0, lastPlanNodeId = 0, transientPlan = false, dependsOnRole = false, 
  parallelModeOK = false, parallelModeNeeded = false, maxParallelHazard = 117 'u'}
#2,parse
#Query結構體
(gdb) p *parse
$2 = {type = T_Query, commandType = CMD_INSERT, querySource = QSRC_ORIGINAL, queryId = 0, canSetTag = true, 
  utilityStmt = 0x0, resultRelation = 1, hasAggs = false, hasWindowFuncs = false, hasTargetSRFs = false, 
  hasSubLinks = false, hasDistinctOn = false, hasRecursive = false, hasModifyingCTE = false, 
  hasForUpdate = false, hasRowSecurity = false, cteList = 0x0, rtable = 0x219e2b8, jointree = 0x21c2aa0, 
  targetList = 0x21c2b20, override = OVERRIDING_NOT_SET, onConflict = 0x0, returningList = 0x0, 
  groupClause = 0x0, groupingSets = 0x0, havingQual = 0x0, windowClause = 0x0, distinctClause = 0x0, 
  sortClause = 0x0, limitOffset = 0x0, limitCount = 0x0, rowMarks = 0x0, setOperations = 0x0, 
  constraintDeps = 0x0, withCheckOptions = 0x0, stmt_location = 0, stmt_len = 69}
#targetList中的元素為TargetEntry *
#在insert語句中,是資料表列
(gdb) p *(parse->targetList)
$3 = {type = T_List, length = 4, head = 0x21c2b00, tail = 0x21c2b90}
(gdb)  p *((TargetEntry *)(parse->targetList->head->data.ptr_value))
$4 = {xpr = {type = T_TargetEntry}, expr = 0x219e5e8, resno = 1, resname = 0x219e338 "id", 
  ressortgroupref = 0, resorigtbl = 0, resorigcol = 0, resjunk = false}
#rtable中的元素是RangeTblEntry *
#在insert操作中,是資料表
(gdb)  p *(parse->rtable)
$5 = {type = T_List, length = 1, head = 0x219e298, tail = 0x219e298}
(gdb) p *((RangeTblEntry *)(parse->rtable->head->data.ptr_value))
$6 = {type = T_RangeTblEntry, rtekind = RTE_RELATION, relid = 26731, relkind = 114 'r', tablesample = 0x0, 
  subquery = 0x0, security_barrier = false, jointype = JOIN_INNER, joinaliasvars = 0x0, functions = 0x0, 
  funcordinality = false, tablefunc = 0x0, values_lists = 0x0, ctename = 0x0, ctelevelsup = 0, 
  self_reference = false, coltypes = 0x0, coltypmods = 0x0, colcollations = 0x0, enrname = 0x0, 
  enrtuples = 0, alias = 0x0, eref = 0x219e0b8, lateral = false, inh = false, inFromCl = false, 
  requiredPerms = 1, checkAsUser = 0, selectedCols = 0x0, insertedCols = 0x21c2938, updatedCols = 0x0, 
  securityQuals = 0x0}
(gdb) p *(((RangeTblEntry *)(parse->rtable->head->data.ptr_value))->insertedCols)
$7 = {nwords = 1, words = 0x21c293c}
#3,parent_root
(gdb) p *parent_root
Cannot access memory at address 0x0
#4,hasRecursion
(gdb) p hasRecursion
$9 = false
#5,tuple_fraction
(gdb) p tuple_fraction
$10 = 0
...
639     if (parse->cteList)
(gdb) 
648     if (parse->hasSubLinks)
(gdb) 
656     inline_set_returning_functions(root);
(gdb) 
662     pull_up_subqueries(root);
(gdb) 
670     if (parse->setOperations)
(gdb) 
680     root->hasJoinRTEs = false;
(gdb) 
681     root->hasLateralRTEs = false;
682     hasOuterJoins = false;
(gdb) 
683     foreach(l, parse->rtable)
(gdb) 
685         RangeTblEntry *rte = lfirst_node(RangeTblEntry, l);
(gdb) 
687         if (rte->rtekind == RTE_JOIN)
(gdb) p *rte
$11 = {type = T_RangeTblEntry, rtekind = RTE_RELATION, relid = 26731, relkind = 114 'r', tablesample = 0x0, 
  subquery = 0x0, security_barrier = false, jointype = JOIN_INNER, joinaliasvars = 0x0, functions = 0x0, 
  funcordinality = false, tablefunc = 0x0, values_lists = 0x0, ctename = 0x0, ctelevelsup = 0, 
  self_reference = false, coltypes = 0x0, coltypmods = 0x0, colcollations = 0x0, enrname = 0x0, 
  enrtuples = 0, alias = 0x0, eref = 0x219e0b8, lateral = false, inh = false, inFromCl = false, 
  requiredPerms = 1, checkAsUser = 0, selectedCols = 0x0, insertedCols = 0x21c2938, updatedCols = 0x0, 
  securityQuals = 0x0}
...
731     parse->targetList = (List *)
(gdb) 
736     if (parse->hasTargetSRFs)
(gdb) p *((TargetEntry *)(parse->targetList->head->data.ptr_value))
$12 = {xpr = {type = T_TargetEntry}, expr = 0x21c3110, resno = 1, resname = 0x219e338 "id", 
  ressortgroupref = 0, resorigtbl = 0, resorigcol = 0, resjunk = false}
(gdb) p *(((TargetEntry *)(parse->targetList->head->data.ptr_value))->expr)
$13 = {type = T_Const}
...
#進入grouping_planner函式,此函式生成root->upper_rels & upper_targets
#注意upper_rels,grouping_planner函式執行完畢,upper_rels最後一個元素會填入相應的值
(gdb) p *root
$22 = {type = T_PlannerInfo, parse = 0x219de98, glob = 0x21c2c20, query_level = 1, parent_root = 0x0, 
  plan_params = 0x0, outer_params = 0x0, simple_rel_array = 0x0, simple_rel_array_size = 0, 
  simple_rte_array = 0x0, all_baserels = 0x0, nullable_baserels = 0x0, join_rel_list = 0x0, 
  join_rel_hash = 0x0, join_rel_level = 0x0, join_cur_level = 0, init_plans = 0x0, cte_plan_ids = 0x0, 
  multiexpr_params = 0x0, eq_classes = 0x0, canon_pathkeys = 0x0, left_join_clauses = 0x0, 
  right_join_clauses = 0x0, full_join_clauses = 0x0, join_info_list = 0x0, append_rel_list = 0x0, 
  rowMarks = 0x0, placeholder_list = 0x0, fkey_list = 0x0, query_pathkeys = 0x0, group_pathkeys = 0x0, 
  window_pathkeys = 0x0, distinct_pathkeys = 0x0, sort_pathkeys = 0x0, part_schemes = 0x0, 
  initial_rels = 0x0, upper_rels = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, upper_targets = {0x0, 0x0, 0x0, 0x0, 
    0x0, 0x0, 0x0}, processed_tlist = 0x0, grouping_map = 0x0, minmax_aggs = 0x0, planner_cxt = 0x219cde0, 
  total_table_pages = 0, tuple_fraction = 0, limit_tuples = 0, qual_security_level = 0, 
  inhTargetKind = INHKIND_NONE, hasJoinRTEs = false, hasLateralRTEs = false, hasDeletedRTEs = false, 
  hasHavingQual = false, hasPseudoConstantQuals = false, hasRecursion = false, wt_param_id = -1, 
  non_recursive_path = 0x0, curOuterRels = 0x0, curOuterParams = 0x0, join_search_private = 0x0, 
  partColsUpdated = false}
(gdb) p inheritance_update
$23 = false
(gdb) p inheritance_update
$24 = false
(gdb) p tuple_fraction
$25 = 0
(gdb) 
...
(gdb) 
1808      tlist = preprocess_targetlist(root);
(gdb) p *root
$27 = {type = T_PlannerInfo, parse = 0x219de98, glob = 0x21c2c20, query_level = 1, parent_root = 0x0, 
  plan_params = 0x0, outer_params = 0x0, simple_rel_array = 0x0, simple_rel_array_size = 0, 
  simple_rte_array = 0x0, all_baserels = 0x0, nullable_baserels = 0x0, join_rel_list = 0x0, 
  join_rel_hash = 0x0, join_rel_level = 0x0, join_cur_level = 0, init_plans = 0x0, cte_plan_ids = 0x0, 
  multiexpr_params = 0x0, eq_classes = 0x0, canon_pathkeys = 0x0, left_join_clauses = 0x0, 
  right_join_clauses = 0x0, full_join_clauses = 0x0, join_info_list = 0x0, append_rel_list = 0x0, 
  rowMarks = 0x0, placeholder_list = 0x0, fkey_list = 0x0, query_pathkeys = 0x0, group_pathkeys = 0x0, 
  window_pathkeys = 0x0, distinct_pathkeys = 0x0, sort_pathkeys = 0x0, part_schemes = 0x0, 
  initial_rels = 0x0, upper_rels = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, upper_targets = {0x0, 0x0, 0x0, 0x0, 
    0x0, 0x0, 0x0}, processed_tlist = 0x21c39e0, grouping_map = 0x0, minmax_aggs = 0x0, 
  planner_cxt = 0x219cde0, total_table_pages = 0, tuple_fraction = 0, limit_tuples = 0, 
  qual_security_level = 0, inhTargetKind = INHKIND_NONE, hasJoinRTEs = false, hasLateralRTEs = false, 
  hasDeletedRTEs = false, hasHavingQual = false, hasPseudoConstantQuals = false, hasRecursion = false, 
  wt_param_id = -1, non_recursive_path = 0x0, curOuterRels = 0x0, curOuterParams = 0x0, 
  join_search_private = 0x0, partColsUpdated = false}
#processed_tlist中的元素為TargetEntry *,也就是欄位Column
(gdb) p *(root->processed_tlist)
$28 = {type = T_List, length = 4, head = 0x21c39c0, tail = 0x21c3a50}
(gdb) p *(root->processed_tlist->head)
$29 = {data = {ptr_value = 0x21c30c0, int_value = 35401920, oid_value = 35401920}, next = 0x21c3a10}
(gdb) p *(TargetEntry *)(root->processed_tlist->head.data->ptr_value)
$30 = {xpr = {type = T_TargetEntry}, expr = 0x21c3110, resno = 1, resname = 0x219e338 "id", 
  ressortgroupref = 0, resorigtbl = 0, resorigcol = 0, resjunk = false}
...
2026      root->upper_targets[UPPERREL_FINAL] = final_target;
(gdb) 
2027      root->upper_targets[UPPERREL_WINDOW] = sort_input_target;
(gdb) 
2028      root->upper_targets[UPPERREL_GROUP_AGG] = grouping_target;
(gdb) 
2035      if (have_grouping)
(gdb) p *final_target
$45 = {type = T_PathTarget, exprs = 0x21c3ee0, sortgrouprefs = 0x21c3ea0, cost = {startup = 0, 
...
(gdb) 
2197          create_modifytable_path(root, final_rel,
(gdb) 
2200                      parse->resultRelation,
(gdb) p *root
$49 = {type = T_PlannerInfo, parse = 0x219de98, glob = 0x21c2c20, query_level = 1, parent_root = 0x0, 
  plan_params = 0x0, outer_params = 0x0, simple_rel_array = 0x0, simple_rel_array_size = 0, 
  simple_rte_array = 0x0, all_baserels = 0x0, nullable_baserels = 0x0, join_rel_list = 0x21c3cf0, 
  join_rel_hash = 0x0, join_rel_level = 0x0, join_cur_level = 0, init_plans = 0x0, cte_plan_ids = 0x0, 
  multiexpr_params = 0x0, eq_classes = 0x0, canon_pathkeys = 0x0, left_join_clauses = 0x0, 
  right_join_clauses = 0x0, full_join_clauses = 0x0, join_info_list = 0x0, append_rel_list = 0x0, 
  rowMarks = 0x0, placeholder_list = 0x0, fkey_list = 0x0, query_pathkeys = 0x0, group_pathkeys = 0x0, 
  window_pathkeys = 0x0, distinct_pathkeys = 0x0, sort_pathkeys = 0x0, part_schemes = 0x0, 
  initial_rels = 0x0, upper_rels = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x21c4320}, upper_targets = {0x0, 0x0, 
    0x21c3e50, 0x21c3e50, 0x0, 0x0, 0x21c3e50}, processed_tlist = 0x21c39e0, grouping_map = 0x0, 
  minmax_aggs = 0x0, planner_cxt = 0x219cde0, total_table_pages = 0, tuple_fraction = 0, limit_tuples = -1, 
  qual_security_level = 0, inhTargetKind = INHKIND_NONE, hasJoinRTEs = false, hasLateralRTEs = false, 
  hasDeletedRTEs = false, hasHavingQual = false, hasPseudoConstantQuals = false, hasRecursion = false, 
  wt_param_id = -1, non_recursive_path = 0x0, curOuterRels = 0x0, curOuterParams = 0x0, 
  join_search_private = 0x0, partColsUpdated = false}
(gdb) finish
Run till exit from #0  grouping_planner (root=0x21c2cb0, inheritance_update=false, tuple_fraction=0)
    at planner.c:2200
subquery_planner (glob=0x21c2c20, parse=0x219de98, parent_root=0x0, hasRecursion=false, tuple_fraction=0)
    at planner.c:972
#退出grouping_planner函式
...
#最終的返回值
#INSERT VALUES語句相對比較簡單,沒有複雜的JOIN/WITH/HAVING/GROUP等語句,這裡只是簡單的返回一個root節點
(gdb) p *root
$17 = {type = T_PlannerInfo, parse = 0x219de98, glob = 0x21c2c20, query_level = 1, parent_root = 0x0, 
  plan_params = 0x0, outer_params = 0x0, simple_rel_array = 0x0, simple_rel_array_size = 0, 
  simple_rte_array = 0x0, all_baserels = 0x0, nullable_baserels = 0x0, join_rel_list = 0x21c3cf0, 
  join_rel_hash = 0x0, join_rel_level = 0x0, join_cur_level = 0, init_plans = 0x0, cte_plan_ids = 0x0, 
  multiexpr_params = 0x0, eq_classes = 0x0, canon_pathkeys = 0x0, left_join_clauses = 0x0, 
  right_join_clauses = 0x0, full_join_clauses = 0x0, join_info_list = 0x0, append_rel_list = 0x0, 
  rowMarks = 0x0, placeholder_list = 0x0, fkey_list = 0x0, query_pathkeys = 0x0, group_pathkeys = 0x0, 
  window_pathkeys = 0x0, distinct_pathkeys = 0x0, sort_pathkeys = 0x0, part_schemes = 0x0, 
  initial_rels = 0x0, upper_rels = {0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x21c4320}, upper_targets = {0x0, 0x0, 
    0x21c3e50, 0x21c3e50, 0x0, 0x0, 0x21c3e50}, processed_tlist = 0x21c39e0, grouping_map = 0x0, 
  minmax_aggs = 0x0, planner_cxt = 0x219cde0, total_table_pages = 0, tuple_fraction = 0, limit_tuples = -1, 
  qual_security_level = 0, inhTargetKind = INHKIND_NONE, hasJoinRTEs = false, hasLateralRTEs = false, 
  hasDeletedRTEs = false, hasHavingQual = false, hasPseudoConstantQuals = false, hasRecursion = false, 
  wt_param_id = -1, non_recursive_path = 0x0, curOuterRels = 0x0, curOuterParams = 0x0, 
  join_search_private = 0x0, partColsUpdated = false}

四、小結

1.重要的資料結構:PlannedStmt/PlannerGlobal/PlannerInfo/RelOptInfo/Path
2.重要的函式:subquery_planner/grouping_planner/create_plan

來自 “ ITPUB部落格 ” ,連結:http://blog.itpub.net/6906/viewspace-2374902/,如需轉載,請註明出處,否則將追究法律責任。

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