PostgreSQL 原始碼解讀（92）- 分割槽表#1（資料插入路由#1）
在PG中,分割槽表透過"繼承"的方式實現,這裡就會存在一個問題,就是在插入資料時,PG如何確定資料應該插入到哪個目標分割槽?在PG中,透過函式ExecPrepareTupleRouting為路由待插入的元組做準備,主要的目的是確定元組所在的分割槽。
一、資料結構
ModifyTable
ModifyTable Node
透過插入、更新或刪除，將子計劃生成的行應用到結果表。
/* ----------------
* ModifyTable node -
* Apply rows produced by subplan(s) to result table(s),
* by inserting, updating, or deleting.
* 透過插入、更新或刪除，將子計劃生成的行應用到結果表。
*
* If the originally named target table is a partitioned table, both
* nominalRelation and rootRelation contain the RT index of the partition
* root, which is not otherwise mentioned in the plan. Otherwise rootRelation
* is zero. However, nominalRelation will always be set, as it's the rel that
* EXPLAIN should claim is the INSERT/UPDATE/DELETE target.
* 如果最初命名的目標表是分割槽表，則nominalRelation和rootRelation都包含分割槽根的RT索引，計劃中沒有另外提到這個索引。
* 否則，根關係為零。但是，總是會設定名義關係，nominalRelation因為EXPLAIN應該宣告的rel是INSERT/UPDATE/DELETE目標關係。
*
* 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.
* 注意，rowMarks和epqParam被假定對所有子計劃有效;
* 它們不能包含任何在子計劃中變化的資訊。
* ----------------
*/
typedef struct ModifyTable
{
Plan plan;
CmdType operation; /* 操作型別;INSERT, UPDATE, or DELETE */
bool canSetTag; /* 是否需要設定tag?do we set the command tag/es_processed? */
Index nominalRelation; /* 用於EXPLAIN的父RT索引;Parent RT index for use of EXPLAIN */
Index rootRelation; /* 根Root RT索引(如目標為分割槽表);Root RT index, if target is partitioned */
bool partColsUpdated; /* 更新了層次結構中的分割槽關鍵字;some part key in hierarchy updated */
List *resultRelations; /* RT索引的整型連結串列;integer list of RT indexes */
int resultRelIndex; /* 計劃連結串列中第一個resultRel的索引;index of first resultRel in plan's list */
int rootResultRelIndex; /* 分割槽表根索引;index of the partitioned table root */
List *plans; /* 生成源資料的計劃連結串列;plan(s) producing source data */
List *withCheckOptionLists; /* 每一個目標表均具備的WCO連結串列;per-target-table WCO lists */
List *returningLists; /* 每一個目標表均具備的RETURNING連結串列;per-target-table RETURNING tlists */
List *fdwPrivLists; /* 每一個目標表的FDW私有資料連結串列;per-target-table FDW private data lists */
Bitmapset *fdwDirectModifyPlans; /* FDW DM計劃索引點陣圖;indices of FDW DM plans */
List *rowMarks; /* rowMarks連結串列;PlanRowMarks (non-locking only) */
int epqParam; /* EvalPlanQual再解析使用的引數ID;ID of Param for EvalPlanQual re-eval */
OnConflictAction onConflictAction; /* ON CONFLICT action */
List *arbiterIndexes; /* 衝突仲裁器索引表;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; /* 已排除偽關係的投影列連結串列;tlist of the EXCLUDED pseudo relation */
} ModifyTable;
ResultRelInfo
ResultRelInfo結構體
每當更新一個現有的關係時，我們必須更新關係上的索引，也許還需要觸發觸發器。ResultRelInfo儲存關於結果關係所需的所有資訊，包括索引。
/*
* ResultRelInfo
* ResultRelInfo結構體
*
* Whenever we update an existing relation, we have to update indexes on the
* relation, and perhaps also fire triggers. ResultRelInfo holds all the
* information needed about a result relation, including indexes.
* 每當更新一個現有的關係時，我們必須更新關係上的索引，也許還需要觸發觸發器。
* ResultRelInfo儲存關於結果關係所需的所有資訊，包括索引。
*
* Normally, a ResultRelInfo refers to a table that is in the query's
* range table; then ri_RangeTableIndex is the RT index and ri_RelationDesc
* is just a copy of the relevant es_relations[] entry. But sometimes,
* in ResultRelInfos used only for triggers, ri_RangeTableIndex is zero
* and ri_RelationDesc is a separately-opened relcache pointer that needs
* to be separately closed. See ExecGetTriggerResultRel.
* 通常，ResultRelInfo是指查詢範圍表中的表;
* ri_RangeTableIndex是RT索引，而ri_RelationDesc只是相關es_relations[]條目的副本。
* 但有時，在只用於觸發器的ResultRelInfos中，ri_RangeTableIndex為零(NULL)，
* 而ri_RelationDesc是一個需要單獨關閉單獨開啟的relcache指標。
* 具體可參考ExecGetTriggerResultRel結構體。
*/
typedef struct ResultRelInfo
{
NodeTag type;
/* result relation's range table index, or 0 if not in range table */
//RTE索引
Index ri_RangeTableIndex;
/* relation descriptor for result relation */
//結果/目標relation的描述符
Relation ri_RelationDesc;
/* # of indices existing on result relation */
//目標關係中索引數目
int ri_NumIndices;
/* array of relation descriptors for indices */
//索引的關係描述符陣列(索引視為一個relation)
RelationPtr ri_IndexRelationDescs;
/* array of key/attr info for indices */
//索引的鍵/屬性陣列
IndexInfo **ri_IndexRelationInfo;
/* triggers to be fired, if any */
//觸發的索引
TriggerDesc *ri_TrigDesc;
/* cached lookup info for trigger functions */
//觸發器函式(快取)
FmgrInfo *ri_TrigFunctions;
/* array of trigger WHEN expr states */
//WHEN表示式狀態的觸發器陣列
ExprState **ri_TrigWhenExprs;
/* optional runtime measurements for triggers */
//可選的觸發器執行期度量器
Instrumentation *ri_TrigInstrument;
/* FDW callback functions, if foreign table */
//FDW回撥函式
struct FdwRoutine *ri_FdwRoutine;
/* available to save private state of FDW */
//可用於儲存FDW的私有狀態
void *ri_FdwState;
/* true when modifying foreign table directly */
//直接更新FDW時為T
bool ri_usesFdwDirectModify;
/* list of WithCheckOption's to be checked */
//WithCheckOption連結串列
List *ri_WithCheckOptions;
/* list of WithCheckOption expr states */
//WithCheckOption表示式連結串列
List *ri_WithCheckOptionExprs;
/* array of constraint-checking expr states */
//約束檢查表示式狀態陣列
ExprState **ri_ConstraintExprs;
/* for removing junk attributes from tuples */
//用於從元組中刪除junk屬性
JunkFilter *ri_junkFilter;
/* list of RETURNING expressions */
//RETURNING表示式連結串列
List *ri_returningList;
/* for computing a RETURNING list */
//用於計算RETURNING連結串列
ProjectionInfo *ri_projectReturning;
/* list of arbiter indexes to use to check conflicts */
//用於檢查衝突的仲裁器索引的列表
List *ri_onConflictArbiterIndexes;
/* ON CONFLICT evaluation state */
//ON CONFLICT解析狀態
OnConflictSetState *ri_onConflict;
/* partition check expression */
//分割槽檢查表示式連結串列
List *ri_PartitionCheck;
/* partition check expression state */
//分割槽檢查表示式狀態
ExprState *ri_PartitionCheckExpr;
/* relation descriptor for root partitioned table */
//分割槽root根表描述符
Relation ri_PartitionRoot;
/* Additional information specific to partition tuple routing */
//額外的分割槽元組路由資訊
struct PartitionRoutingInfo *ri_PartitionInfo;
} ResultRelInfo;
PartitionRoutingInfo
PartitionRoutingInfo結構體
分割槽路由資訊,用於將元組路由到表分割槽的結果關係資訊。
/*
* PartitionRoutingInfo
* PartitionRoutingInfo - 分割槽路由資訊
*
* Additional result relation information specific to routing tuples to a
* table partition.
* 用於將元組路由到表分割槽的結果關係資訊。
*/
typedef struct PartitionRoutingInfo
{
/*
* Map for converting tuples in root partitioned table format into
* partition format, or NULL if no conversion is required.
* 對映，用於將根分割槽表格式的元組轉換為分割槽格式，如果不需要轉換，則轉換為NULL。
*/
TupleConversionMap *pi_RootToPartitionMap;
/*
* Map for converting tuples in partition format into the root partitioned
* table format, or NULL if no conversion is required.
* 對映，用於將分割槽格式的元組轉換為根分割槽表格式，如果不需要轉換，則轉換為NULL。
*/
TupleConversionMap *pi_PartitionToRootMap;
/*
* Slot to store tuples in partition format, or NULL when no translation
* is required between root and partition.
* 以分割槽格式儲存元組的slot.在根分割槽和分割槽之間不需要轉換時為NULL。
*/
TupleTableSlot *pi_PartitionTupleSlot;
} PartitionRoutingInfo;
TupleConversionMap
TupleConversionMap結構體,用於儲存元組轉換對映資訊.
typedef struct TupleConversionMap
{
TupleDesc indesc; /* 源行型別的描述符;tupdesc for source rowtype */
TupleDesc outdesc; /* 結果行型別的描述符;tupdesc for result rowtype */
AttrNumber *attrMap; /* 輸入欄位的索引資訊,0表示NULL;indexes of input fields, or 0 for null */
Datum *invalues; /* 析構源資料的工作空間;workspace for deconstructing source */
bool *inisnull; //是否為NULL標記陣列
Datum *outvalues; /* 構造結果的工作空間;workspace for constructing result */
bool *outisnull; //null標記
} TupleConversionMap;
二、原始碼解讀
ExecPrepareTupleRouting函式確定要插入slot中的tuple所屬的分割槽，同時修改mtstate和estate等相關資訊,為後續實際的插入作準備。
/*
* ExecPrepareTupleRouting --- prepare for routing one tuple
* ExecPrepareTupleRouting --- 為路由一個元組做準備
*
* Determine the partition in which the tuple in slot is to be inserted,
* and modify mtstate and estate to prepare for it.
* 確定要插入slot中tuple的分割槽，並修改mtstate和estate以為插入作準備。
*
* Caller must revert the estate changes after executing the insertion!
* In mtstate, transition capture changes may also need to be reverted.
* 呼叫方必須在執行插入之後恢復estate中被修改的屬性值!
* 在mtstate中，轉換捕獲更改也可能需要恢復。
*
* Returns a slot holding the tuple of the partition rowtype.
* 返回包含分割槽rowtype元組的槽位。
*/
static TupleTableSlot *
ExecPrepareTupleRouting(ModifyTableState *mtstate,
EState *estate,
PartitionTupleRouting *proute,
ResultRelInfo *targetRelInfo,
TupleTableSlot *slot)
{
ModifyTable *node;//ModifyTable節點
int partidx;//分割槽索引
ResultRelInfo *partrel;//ResultRelInfo結構體指標(陣列)
HeapTuple tuple;//元組
/*
* Determine the target partition. If ExecFindPartition does not find a
* partition after all, it doesn't return here; otherwise, the returned
* value is to be used as an index into the arrays for the ResultRelInfo
* and TupleConversionMap for the partition.
* 確定目標分割槽。
* 如果ExecFindPartition最終沒有找到分割槽，它不會在這裡返回;
* 否則，返回值將用作分割槽的ResultRelInfo和TupleConversionMap陣列的索引。
*/
partidx = ExecFindPartition(targetRelInfo,
proute->partition_dispatch_info,
slot,
estate);
Assert(partidx >= 0 && partidx < proute->num_partitions);
/*
* Get the ResultRelInfo corresponding to the selected partition; if not
* yet there, initialize it.
* 獲取與所選分割槽對應的ResultRelInfo;如果還沒有，則初始化。
*/
partrel = proute->partitions[partidx];
if (partrel == NULL)
partrel = ExecInitPartitionInfo(mtstate, targetRelInfo,
proute, estate,
partidx);
/*
* Check whether the partition is routable if we didn't yet
* 檢查分割槽是否可路由
*
* Note: an UPDATE of a partition key invokes an INSERT that moves the
* tuple to a new partition. This check would be applied to a subplan
* partition of such an UPDATE that is chosen as the partition to route
* the tuple to. The reason we do this check here rather than in
* ExecSetupPartitionTupleRouting is to avoid aborting such an UPDATE
* unnecessarily due to non-routable subplan partitions that may not be
* chosen for update tuple movement after all.
* 注意:分割槽鍵的更新呼叫將元組移動到新分割槽的插入。
* 此檢查將應用於此類更新的子計劃分割槽，該分割槽被選擇為將元組路由到的分割槽。
* 在這裡而不是在ExecSetupPartitionTupleRouting中執行此檢查的原因是
為了避免由於無法路由的子計劃分割槽而不必要地中止這樣的更新，這些分割槽可能最終不會被選擇用於更新元組移動。
*/
if (!partrel->ri_PartitionReadyForRouting)
{
/* Verify the partition is a valid target for INSERT. */
//驗證分割槽是否可用於INSERT
CheckValidResultRel(partrel, CMD_INSERT);
/* Set up information needed for routing tuples to the partition. */
//設定將元組路由到分割槽所需的資訊。
ExecInitRoutingInfo(mtstate, estate, proute, partrel, partidx);
}
/*
* Make it look like we are inserting into the partition.
* 讓它看起來像是插入到分割槽中。
*/
estate->es_result_relation_info = partrel;
/* Get the heap tuple out of the given slot. */
//從給定的slot中獲取heap tuple
tuple = ExecMaterializeSlot(slot);
/*
* If we're capturing transition tuples, we might need to convert from the
* partition rowtype to parent rowtype.
* 如果正在捕獲轉換元組，可能需要將分割槽行型別轉換為根分割槽表的行型別。
*/
if (mtstate->mt_transition_capture != NULL)
{
if (partrel->ri_TrigDesc &&
partrel->ri_TrigDesc->trig_insert_before_row)
{
/*
* If there are any BEFORE triggers on the partition, we'll have
* to be ready to convert their result back to tuplestore format.
* 如果分割槽上有BEFORE觸發器，必須準備將它們的結果轉換回tuplestore格式。
*/
mtstate->mt_transition_capture->tcs_original_insert_tuple = NULL;
mtstate->mt_transition_capture->tcs_map =
TupConvMapForLeaf(proute, targetRelInfo, partidx);
}
else
{
/*
* Otherwise, just remember the original unconverted tuple, to
* avoid a needless round trip conversion.
* 否則，只需記住原始的未轉換元組，以避免不必要的來回轉換。
*/
mtstate->mt_transition_capture->tcs_original_insert_tuple = tuple;
mtstate->mt_transition_capture->tcs_map = NULL;
}
}
if (mtstate->mt_oc_transition_capture != NULL)
{
mtstate->mt_oc_transition_capture->tcs_map =
TupConvMapForLeaf(proute, targetRelInfo, partidx);
}
/*
* Convert the tuple, if necessary.
* 如需要,轉換元組
*/
ConvertPartitionTupleSlot(proute->parent_child_tupconv_maps[partidx],
tuple,
proute->partition_tuple_slot,
&slot);
/* Initialize information needed to handle ON CONFLICT DO UPDATE. */
//如為ON CONFLICT DO UPDATE模式,則初始化相關資訊
Assert(mtstate != NULL);
node = (ModifyTable *) mtstate->ps.plan;
if (node->onConflictAction == ONCONFLICT_UPDATE)
{
Assert(mtstate->mt_existing != NULL);
ExecSetSlotDescriptor(mtstate->mt_existing,
RelationGetDescr(partrel->ri_RelationDesc));
Assert(mtstate->mt_conflproj != NULL);
ExecSetSlotDescriptor(mtstate->mt_conflproj,
partrel->ri_onConflict->oc_ProjTupdesc);
}
return slot;
}
/*
* ExecFetchSlotHeapTuple - fetch HeapTuple representing the slot's content
* ExecFetchSlotHeapTuple - 根據slot提取HeapTuple
*
* The returned HeapTuple represents the slot's content as closely as
* possible.
* 返回的HeapTuple儘可能就是slot的內容。
*
* If materialize is true, the contents of the slots will be made independent
* from the underlying storage (i.e. all buffer pins are release, memory is
* allocated in the slot's context).
* 如果materialize為T，slot的內容將獨立於底層儲存(即釋放所有緩衝區pin，在slot的上下文中分配記憶體)。
*
* If shouldFree is not-NULL it'll be set to true if the returned tuple has
* been allocated in the calling memory context, and must be freed by the
* caller (via explicit pfree() or a memory context reset).
* 如果shouldFree not-NULL，那麼如果返回的元組已經在呼叫記憶體上下文中分配，
* 並且必須由呼叫方釋放(透過顯式pfree()或記憶體上下文重置)。
*
* NB: If materialize is true, modifications of the returned tuple are
* allowed. But it depends on the type of the slot whether such modifications
* will also affect the slot's contents. While that is not the nicest
* behaviour, all such modifcations are in the process of being removed.
* 注意:如果materialize為T，則允許修改返回的元組。
* 但這取決於slot的型別，這種修改是否也會影響slot的內容。
* 雖然這不是最好的行為，但所有這些修改都在被移除的過程中。
*/
HeapTuple
ExecFetchSlotHeapTuple(TupleTableSlot *slot, bool materialize, bool *shouldFree)
{
/*
* sanity checks
* 安全檢查
*/
Assert(slot != NULL);
Assert(!TTS_EMPTY(slot));
/* Materialize the tuple so that the slot "owns" it, if requested. */
//物化元組，以便slot“擁有”它(如要求)。
if (materialize)
slot->tts_ops->materialize(slot);
if (slot->tts_ops->get_heap_tuple == NULL)
{
if (shouldFree)
*shouldFree = true;
return slot->tts_ops->copy_heap_tuple(slot);//返回slot複製
}
else
{
if (shouldFree)
*shouldFree = false;
return slot->tts_ops->get_heap_tuple(slot);//直接返回slot
}
}
三、跟蹤分析
測試指令碼如下
-- Hash Partition
drop table if exists t_hash_partition;
create table t_hash_partition (c1 int not null,c2 varchar(40),c3 varchar(40)) partition by hash(c1);
create table t_hash_partition_1 partition of t_hash_partition for values with (modulus 6,remainder 0);
create table t_hash_partition_2 partition of t_hash_partition for values with (modulus 6,remainder 1);
create table t_hash_partition_3 partition of t_hash_partition for values with (modulus 6,remainder 2);
create table t_hash_partition_4 partition of t_hash_partition for values with (modulus 6,remainder 3);
create table t_hash_partition_5 partition of t_hash_partition for values with (modulus 6,remainder 4);
create table t_hash_partition_6 partition of t_hash_partition for values with (modulus 6,remainder 5);
-- delete from t_hash_partition where c1 = 0;
insert into t_hash_partition(c1,c2,c3) VALUES(0,'HASH0','HAHS0');
啟動gdb,設定斷點,進入ExecPrepareTupleRouting
(gdb) b ExecPrepareTupleRouting
Breakpoint 1 at 0x710b1e: file nodeModifyTable.c, line 1712.
(gdb) c
Continuing.
Breakpoint 1, ExecPrepareTupleRouting (mtstate=0x1e4de60, estate=0x1e4daf8, proute=0x1e4eb48, targetRelInfo=0x1e4dd48,
slot=0x1e4e4e0) at nodeModifyTable.c:1712
1712 partidx = ExecFindPartition(targetRelInfo,
檢視函式呼叫棧
ExecPrepareTupleRouting在ExecModifyTable Node中被呼叫,為後續的插入作準備.
(gdb) bt
#0 ExecPrepareTupleRouting (mtstate=0x1e4de60, estate=0x1e4daf8, proute=0x1e4eb48, targetRelInfo=0x1e4dd48, slot=0x1e4e4e0)
at nodeModifyTable.c:1712
#1 0x0000000000711602 in ExecModifyTable (pstate=0x1e4de60) at nodeModifyTable.c:2157
#2 0x00000000006e4c30 in ExecProcNodeFirst (node=0x1e4de60) at execProcnode.c:445
#3 0x00000000006d9974 in ExecProcNode (node=0x1e4de60) at ../../../src/include/executor/executor.h:237
#4 0x00000000006dc22d in ExecutePlan (estate=0x1e4daf8, planstate=0x1e4de60, use_parallel_mode=false,
operation=CMD_INSERT, sendTuples=false, numberTuples=0, direction=ForwardScanDirection, dest=0x1e67e90,
execute_once=true) at execMain.c:1723
#5 0x00000000006d9f5c in standard_ExecutorRun (queryDesc=0x1e39d68, direction=ForwardScanDirection, count=0,
execute_once=true) at execMain.c:364
#6 0x00000000006d9d7f in ExecutorRun (queryDesc=0x1e39d68, direction=ForwardScanDirection, count=0, execute_once=true)
at execMain.c:307
#7 0x00000000008cbdb3 in ProcessQuery (plan=0x1e67d18,
sourceText=0x1d60ec8 "insert into t_hash_partition(c1,c2,c3) VALUES(0,'HASH0','HAHS0');", params=0x0, queryEnv=0x0,
dest=0x1e67e90, completionTag=0x7ffdcf148b20 "") at pquery.c:161
#8 0x00000000008cd6f9 in PortalRunMulti (portal=0x1dc6538, isTopLevel=true, setHoldSnapshot=false, dest=0x1e67e90,
altdest=0x1e67e90, completionTag=0x7ffdcf148b20 "") at pquery.c:1286
#9 0x00000000008cccb9 in PortalRun (portal=0x1dc6538, count=9223372036854775807, isTopLevel=true, run_once=true,
dest=0x1e67e90, altdest=0x1e67e90, completionTag=0x7ffdcf148b20 "") at pquery.c:799
#10 0x00000000008c6b1e in exec_simple_query (
query_string=0x1d60ec8 "insert into t_hash_partition(c1,c2,c3) VALUES(0,'HASH0','HAHS0');") at postgres.c:1145
#11 0x00000000008cae70 in PostgresMain (argc=1, argv=0x1d8aba8, dbname=0x1d8aa10 "testdb", username=0x1d5dba8 "xdb")
at postgres.c:4182
找到該元組所在的分割槽
(gdb) n
1716 Assert(partidx >= 0 && partidx < proute->num_partitions);
(gdb) p partidx
$1 = 2
獲取與所選分割槽對應的ResultRelInfo;如果還沒有，則初始化
(gdb) n
1722 partrel = proute->partitions[partidx];
(gdb)
1723 if (partrel == NULL)
(gdb) p *partrel
Cannot access memory at address 0x0
(gdb) n
1724 partrel = ExecInitPartitionInfo(mtstate, targetRelInfo,
初始化後的partrel
(gdb) p *partrel
$2 = {type = T_ResultRelInfo, ri_RangeTableIndex = 1, ri_RelationDesc = 0x1e7c940, ri_NumIndices = 0,
ri_IndexRelationDescs = 0x0, ri_IndexRelationInfo = 0x0, ri_TrigDesc = 0x0, ri_TrigFunctions = 0x0,
ri_TrigWhenExprs = 0x0, ri_TrigInstrument = 0x0, ri_FdwRoutine = 0x0, ri_FdwState = 0x0, ri_usesFdwDirectModify = false,
ri_WithCheckOptions = 0x0, ri_WithCheckOptionExprs = 0x0, ri_ConstraintExprs = 0x0, ri_junkFilter = 0x0,
ri_returningList = 0x0, ri_projectReturning = 0x0, ri_onConflictArbiterIndexes = 0x0, ri_onConflict = 0x0,
ri_PartitionCheck = 0x1e4f538, ri_PartitionCheckExpr = 0x0, ri_PartitionRoot = 0x1e7c2f8,
ri_PartitionReadyForRouting = true}
目標分割槽描述符-->t_hash_partition_3
(gdb) p *partrel->ri_RelationDesc
$3 = {rd_node = {spcNode = 1663, dbNode = 16402, relNode = 16995}, rd_smgr = 0x1e34510, rd_refcnt = 1, rd_backend = -1,
rd_islocaltemp = false, rd_isnailed = false, rd_isvalid = true, rd_indexvalid = 0 '\000', rd_statvalid = false,
rd_createSubid = 0, rd_newRelfilenodeSubid = 0, rd_rel = 0x1e7c1e0, rd_att = 0x1e7cb58, rd_id = 16995, rd_lockInfo = {
lockRelId = {relId = 16995, dbId = 16402}}, rd_rules = 0x0, rd_rulescxt = 0x0, trigdesc = 0x0, rd_rsdesc = 0x0,
rd_fkeylist = 0x0, rd_fkeyvalid = false, rd_partkeycxt = 0x0, rd_partkey = 0x0, rd_pdcxt = 0x0, rd_partdesc = 0x0,
rd_partcheck = 0x1e7aa30, rd_indexlist = 0x0, rd_oidindex = 0, rd_pkindex = 0, rd_replidindex = 0, rd_statlist = 0x0,
rd_indexattr = 0x0, rd_projindexattr = 0x0, rd_keyattr = 0x0, rd_pkattr = 0x0, rd_idattr = 0x0, rd_projidx = 0x0,
rd_pubactions = 0x0, rd_options = 0x0, rd_index = 0x0, rd_indextuple = 0x0, rd_amhandler = 0, rd_indexcxt = 0x0,
rd_amroutine = 0x0, rd_opfamily = 0x0, rd_opcintype = 0x0, rd_support = 0x0, rd_supportinfo = 0x0, rd_indoption = 0x0,
rd_indexprs = 0x0, rd_indpred = 0x0, rd_exclops = 0x0, rd_exclprocs = 0x0, rd_exclstrats = 0x0, rd_amcache = 0x0,
rd_indcollation = 0x0, rd_fdwroutine = 0x0, rd_toastoid = 0, pgstat_info = 0x1de40b0}
------------------
testdb=# select oid,relname from pg_class where oid=16995;
oid | relname
-------+--------------------
16995 | t_hash_partition_3
(1 row)
-----------------
該分割槽是可路由的
(gdb) p partrel->ri_PartitionReadyForRouting
$4 = true
設定estate變數(讓它看起來像是插入到分割槽中)/物化tuple
(gdb) n
1751 estate->es_result_relation_info = partrel;
(gdb)
1754 tuple = ExecMaterializeSlot(slot);
(gdb)
1760 if (mtstate->mt_transition_capture != NULL)
(gdb) p tuple
$5 = (HeapTuple) 0x1e4f4e0
(gdb) p *tuple
$6 = {t_len = 40, t_self = {ip_blkid = {bi_hi = 65535, bi_lo = 65535}, ip_posid = 0}, t_tableOid = 0, t_data = 0x1e4f4f8}
(gdb)
(gdb) p *tuple->t_data
$7 = {t_choice = {t_heap = {t_xmin = 160, t_xmax = 4294967295, t_field3 = {t_cid = 2249, t_xvac = 2249}}, t_datum = {
datum_len_ = 160, datum_typmod = -1, datum_typeid = 2249}}, t_ctid = {ip_blkid = {bi_hi = 65535, bi_lo = 65535},
ip_posid = 0}, t_infomask2 = 3, t_infomask = 2, t_hoff = 24 '\030', t_bits = 0x1e4f50f ""}
mtstate->mt_transition_capture 為NULL,無需處理相關資訊
(gdb) p mtstate->mt_transition_capture
$8 = (struct TransitionCaptureState *) 0x0
1783 if (mtstate->mt_oc_transition_capture != NULL)
(gdb)
如需要,轉換元組
1792 ConvertPartitionTupleSlot(proute->parent_child_tupconv_maps[partidx],
(gdb)
1798 Assert(mtstate != NULL);
(gdb)
1799 node = (ModifyTable *) mtstate->ps.plan;
(gdb) p *mtstate
$9 = {ps = {type = T_ModifyTableState, plan = 0x1e59838, state = 0x1e4daf8, ExecProcNode = 0x711056 <ExecModifyTable>,
ExecProcNodeReal = 0x711056 <ExecModifyTable>, instrument = 0x0, worker_instrument = 0x0, worker_jit_instrument = 0x0,
qual = 0x0, lefttree = 0x0, righttree = 0x0, initPlan = 0x0, subPlan = 0x0, chgParam = 0x0,
ps_ResultTupleSlot = 0x1e4ede8, ps_ExprContext = 0x0, ps_ProjInfo = 0x0, scandesc = 0x0}, operation = CMD_INSERT,
canSetTag = true, mt_done = false, mt_plans = 0x1e4e078, mt_nplans = 1, mt_whichplan = 0, resultRelInfo = 0x1e4dd48,
rootResultRelInfo = 0x0, mt_arowmarks = 0x1e4e098, mt_epqstate = {estate = 0x0, planstate = 0x0, origslot = 0x1e4e4e0,
plan = 0x1e59588, arowMarks = 0x0, epqParam = 0}, fireBSTriggers = false, mt_existing = 0x0, mt_excludedtlist = 0x0,
mt_conflproj = 0x0, mt_partition_tuple_routing = 0x1e4eb48, mt_transition_capture = 0x0, mt_oc_transition_capture = 0x0,
mt_per_subplan_tupconv_maps = 0x0}
返回slot,完成呼叫
(gdb) n
1800 if (node->onConflictAction == ONCONFLICT_UPDATE)
(gdb)
1810 return slot;
(gdb)
1811 }
DONE!
ExecFindPartition函式是主要的實現函式,下節再行介紹
四、參考資料
PG 11.1 Source Code.
注: doxygen上的原始碼與PG 11.1原始碼並不一致,本節基於11.1進行分析.
來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/6906/viewspace-2374798/，如需轉載，請註明出處，否則將追究法律責任。
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