[20190531]lob型別pctversion 和 retention.txt

lfree發表於2019-06-07

[20190531]lob型別pctversion 和 retention.txt

--//昨天看Secrets of the oracle database 電子書,發現lob型別的pctversion 和 retention測試,在12c測試看看.

1.環境:
SCOTT@test01p> @ ver1
PORT_STRING                    VERSION        BANNER                                                                               CON_ID
------------------------------ -------------- -------------------------------------------------------------------------------- ----------
IBMPC/WIN_NT64-9.1.0           12.2.0.1.0     Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production              0

SCOTT@test01p> SHOW PARAMETER undo_retention
NAME           TYPE    VALUE
-------------- ------- ------
undo_retention integer 3600

2.測試:
CREATE TABLE blog ( username VARCHAR2(30), date_time DATE, text CLOB, img BLOB)
LOB (text) STORE AS blog_text_clob (RETENTION),
LOB (img) STORE  AS blog_img_blob (PCTVERSION 10);

SCOTT@test01p> SELECT COLUMN_NAME,pctversion, retention FROM user_lobs WHERE table_name='BLOG';
COLUMN_NAME          PCTVERSION  RETENTION
-------------------- ---------- ----------
TEXT
IMG                          10

SCOTT@test01p> SELECT COLUMN_NAME,pctversion, retention FROM dba_lobs WHERE table_name='BLOG';
COLUMN_NAME          PCTVERSION  RETENTION
-------------------- ---------- ----------
TEXT
IMG                          20

--//顯示與書測試不符合.是不是可以這麼認為PCTVERSION不顯示就是採用RETENTION,還是12c的pdb導致的情況呢?

SELECT object_name, flags
  FROM sys.lob$ l, dba_objects o
 WHERE l.lobj# = o.object_id
   AND o.object_name IN ('BLOG_TEXT_CLOB', 'BLOG_IMG_BLOB');

OBJECT_NAME               FLAGS
-------------------- ----------
BLOG_IMG_BLOB              1089
BLOG_TEXT_CLOB             1121

--//這個測試也是與書測試不符合.
--//書中執行結果如下:
OBJECT_NAME               FLAGS
-------------------- ----------
BLOG_IMG_BLOB                65
BLOG_TEXT_CLOB               97

--//1089-65 = 1024
--//1121-97 = 1024
--//我估計lob 12c使用SECUREFILE的緣故. flag=1024表示SECUREFILE型別.

SCOTT@test01p> @ ddl scott.blog
C100
--------------------------------------------------------------------
  CREATE TABLE "SCOTT"."BLOG"
   (    "USERNAME" VARCHAR2(30),
        "DATE_TIME" DATE,
        "TEXT" CLOB,
        "IMG" BLOB
   ) SEGMENT CREATION DEFERRED
  PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255
 NOCOMPRESS LOGGING
  TABLESPACE "USERS"
 LOB ("TEXT") STORE AS SECUREFILE "BLOG_TEXT_CLOB"(
  TABLESPACE "USERS" ENABLE STORAGE IN ROW CHUNK 8192
  NOCACHE LOGGING  NOCOMPRESS  KEEP_DUPLICATES )
 LOB ("IMG") STORE AS SECUREFILE "BLOG_IMG_BLOB"(
  TABLESPACE "USERS" ENABLE STORAGE IN ROW CHUNK 8192
  NOCACHE LOGGING  NOCOMPRESS  KEEP_DUPLICATES ) ;

--//從書中摘要:
There's the missing piece of information: if retention is specified, then LOB$.FLAGS, which is obviously a bit vector,
is incremented by 32. So the bit that represents 25 is set if RETENTION is  used. Leveraging our finding, we can write
the following query, which uses the function BITAND to detect whether RETENTION is enabled:

SELECT owner, object_name,
       CASE WHEN bitand(l.flags, 32) = 0 THEN l.pctversion$
        ELSE NULL
       END AS pctversion,
       CASE WHEN bitand(l.flags, 32) = 32 THEN l.retention
        ELSE NULL
       END AS retention
  FROM sys.lob$ l, dba_objects o
 WHERE l.lobj#                  = o.object_id
   AND o.object_type            = 'LOB'
   AND OWNER                    = 'SCOTT';

OWNER OBJECT_NAME          PCTVERSION  RETENTION
----- -------------------- ---------- ----------
SCOTT BLOG_IMG_BLOB                10
SCOTT BLOG_TEXT_CLOB                        3600

--//感覺oracle到12c這樣一些細節都沒有解決好不應該.不過注意看這樣查詢RETENTION有數值,說明dba_lobs檢視定義有問題.

SCOTT@test01p> SELECT owner,object_name,object_id,data_object_id FROM dba_objects where owner='SCOTT' and object_type='LOB';
OWNER OBJECT_NAME           OBJECT_ID DATA_OBJECT_ID
----- -------------------- ---------- --------------
SCOTT BLOG_IMG_BLOB             24443          24443
SCOTT BLOG_TEXT_CLOB            24441          24441

SCOTT@test01p> select * from sys.lob$ where lobj# in (24441,24443);
      OBJ#       COL#    INTCOL#      LOBJ#      PART#       IND#        TS#      FILE#     BLOCK#      CHUNK PCTVERSION$      FLAGS PROPERTY  RETENTION  FREEPOOLS     SPARE1     SPARE2 SPARE3
---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- ----------- ---------- -------- ---------- ---------- ---------- ---------- -------
     24440          3          3      24441          0      24442          4          0          0          1          10       1121     6146       3600          0
     24440          4          4      24443          0      24444          4          0          0          1          20       1089     6146          4          0
--//很明顯RETENTION定義是有值的,很奇怪的地方是BLOG_IMG_BLOB的RETENTION=4.
--//按照道理僅僅透過flags標識來確定定義時採用pctversion還是retention.

3.繼續測試:
SCOTT@test01p> select text_vc from dba_views where view_name like 'DBA_LOBS';
TEXT_VC
----------------------------------------------------------------------
select u.name, o.name,
       decode(bitand(c.property, 1), 1, ac.name, c.name), lo.name,
       decode(bitand(l.property, 8),
           8, decode(l.ts#, 2147483647, ts1.name, ts.name), ts.name),
       io.name,
       l.chunk * decode(bitand(l.property, 8), 8, ts1.blocksize,
                        ts.blocksize),
       decode(bitand(l.flags, 32), 0, l.pctversion$, to_number(NULL)),
       decode(bitand(l.flags, 32), 32,
              decode(bitand(l.property, 2048), 2048, to_number(NULL),
                     l.retention), to_number(NULL)),
       decode(l.freepools, 0, to_number(NULL), 65534, to_number(NULL),
              65535, to_number(NULL), l.freepools),
       decode(bitand(l.flags, 795), 1, 'NO', 2, 'NO', 8, 'CACHEREADS',
                                   16, 'CACHEREADS', 256, 'YES',
                                   512, 'YES', 'YES'),
       decode(bitand(l.flags, 786), 2, 'NO', 16, 'NO', 256, 'NO', 512,
                                       'YES', 'YES'),
       decode(bitand(l.flags, 4096), 4096, 'YES',
              decode(bitand(l.property, 2048), 2048, 'NO', 'NONE')),
       decode(bitand(l.flags, 57344), 8192, 'LOW', 16384, 'MEDIUM', 32768,
              'HIGH',
              decode(bitand(l.property, 2048), 2048, 'NO', 'NONE')),
       decode(bitand(l.flags, 458752), 65536, 'LOB', 131072, 'OBJECT',
              327680, 'LOB VALIDATE', 393216, 'OBJECT VALIDATE',
              decode(bitand(l.property, 2048), 2048, 'NO', 'NONE')),
       decode(bitand(l.property, 2), 2, 'YES', 'NO'),
       decode(c.type#, 113, 'NOT APPLICABLE ',
              decode(bitand(l.property, 512), 512,
                     'ENDIAN SPECIFIC', 'ENDIAN NEUTRAL ')),
       decode(bitand(ta.property, 32), 32, 'YES', 'NO'),
       decode(bitand(l.property, 2048), 2048, 'YES', 'NO'),
       decode(bitand(l.property, 4096), 4096, 'NO',
              decode(bitand(ta.property, 32), 32, 'N/A', 'YES')),
       decode (bitand(l.property, 2048),
               2048,
               decode(bitand(ta.property, 17179869184), 17179869184,
                      decode(ds.lobret_stg, to_number(NULL), 'DEFAULT',
                                            0, 'NONE', 1, 'AUTO',
                                            2, 'MIN', 3, 'MAX',
                                            4, 'DEFAULT', 'INVALID'),
                      decode(s.lists, 0, 'NONE', 1, 'AUTO',
                                      2, 'MIN', 3, 'MAX',
                                      4, 'DEFAULT', 'INVALID')),
               decode(bitand(l.flags, 32), 32, 'YES', 'NO')),
       decode (bitand(l.property, 2048),
               2048,
               decode(bitand(ta.property, 17179869184), 17179869184,
                      decode(ds.lobret_stg, 2, ds.mintim_stg, to_number(NULL)),
                      decode(s.lists, 2, s.groups, to_number(NULL))))
from sys.obj$ o, sys.col$ c, sys.attrcol$ ac, sys.tab$ ta, sys.lob$ l,
     sys.obj$ lo, sys.obj$ io, sys.user$ u, sys.ts$ ts, sys.ts$ ts1,
     sys.seg$ s, sys.deferred_stg$ ds
where o.owner# = u.user#
  and bitand(o.flags, 128) = 0
  and o.obj# = c.obj#
  and c.obj# = l.obj#
  and c.intcol# = l.intcol#
  and l.lobj# = lo.obj#
  and l.ind# = io.obj#
  and l.ts# = ts.ts#(+)
  and u.tempts# = ts1.ts#
  and c.obj# = ac.obj#(+)
  and c.intcol# = ac.intcol#(+)
  and bitand(c.property,32768) != 32768           /* not unused column */
  and o.obj# = ta.obj#
  and bitand(ta.property, 32) != 32           /* not partitioned table */
  and l.file# = s.file#(+)
  and l.block# = s.block#(+)
  and l.ts# = s.ts#(+)
  and l.lobj# = ds.obj#(+)
union all
select u.name, o.name,
       decode(bitand(c.property, 1), 1, ac.name, c.name),
       lo.name,
       NVL(ts1.name,
        (select ts2.name
        from    ts$ ts2, partobj$ po
        where   o.obj# = po.obj# and po.defts# = ts2.ts#)),
       io.name,
       plob.defchunk * NVL(ts1.blocksize, NVL((
        select ts2.blocksize
        from   sys.ts$ ts2, sys.lobfrag$ lf
        where  l.lo
--//暈!!竟然顯示不全.完整可以檢視D:\app\oracle\product\12.2.0\dbhome_1\rdbms\admin\cdcore.sql,不再貼出.
--//decode(bitand(l.flags, 32), 0, l.pctversion$, to_number(NULL)) 對應欄位 PCTVERSION.
--//decode(bitand(l.flags, 32), 32,decode(bitand(l.property, 2048), 2048, to_number(NULL),l.retention), to_number(NULL)) 對應欄位RETENTION.
--//直接帶入值看看:
SCOTT@test01p> select decode(bitand(97, 32), 32,decode(bitand(6146, 2048), 2048, to_number(NULL),3600), to_number(NULL)) n10 from dual ;
                  N10
---------------------


--//6146=0x1802, 2048=0x800  1024=0x400  32=0x20
--//看dcore.bsq中lob$表定義:
  flags         number not null,                           /* 0x0000 = CACHE */
                                                 /* 0x0001 = NOCACHE LOGGING */
                                               /* 0x0002 = NOCACHE NOLOGGING */
                                             /* 0x0008 = CACHE READS LOGGING */
                                           /* 0x0010 = CACHE READS NOLOGGING */
                                          /* 0x0020 = retention is specified */
                                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                                       /* 0x0040 = Index key holds timestamp */
                                      /* 0x0080 = need to drop the freelists */
                                                 /* 0x0100 = CACHE NOLOGGING */
                                                   /* 0x0200 = CACHE LOGGING */
                                                            /* 0x0400 = SYNC */
                                                           /* 0x0800 = ASYNC */
                                                      /* 0x1000 = Encryption */
                                               /* 0x2000 = Compression - Low */
                                            /* 0x4000 = Compression - Medium */
                                              /* 0x8000 = Compression - High */
                                             /* 0x10000 = Sharing: LOB level */
                                          /* 0x20000 = Sharing: Object level */
                                              /* 0x40000 = Sharing: Validate */

  property      number not null,           /* 0x00 = user defined lob column */
                                    /* 0x01 = kernel column(s) stored as lob */
                                     /* 0x02 = user lob column with row data */
                                            /* 0x04 = partitioned LOB column */
                                   /* 0x0008 = LOB In Global Temporary Table */
                                          /* 0x0010 = Session-specific table */
                                      /* 0x0020 = lob with compressed header */
                                        /* 0x0040 = lob using shared segment */
                                  /* 0x0080 = first lob using shared segment */
                                   /* 0x0100 = klob and inline image coexist */
                                /* 0x0200 = LOB data in little endian format */
                                                   /* 0x0800 = 11g LOCAL lob */
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~什麼意思??
                                        /* 0x1000 = Delayed Segment Creation */
                                                  /*0x2000 = 32K inline lobs */

4.不指定看看:

CREATE TABLE blog ( username VARCHAR2(30), date_time DATE, text CLOB, img BLOB)
LOB (text) STORE AS blog_text_clob ,
LOB (img) STORE  AS blog_img_blob ;

SCOTT@test01p> SELECT owner,object_name,object_id,data_object_id FROM dba_objects where owner='SCOTT' and object_type='LOB';
OWNER                OBJECT_NAME           OBJECT_ID DATA_OBJECT_ID
-------------------- -------------------- ---------- --------------
SCOTT                BLOG_IMG_BLOB             24448          24448
SCOTT                BLOG_TEXT_CLOB            24446          24446

SCOTT@test01p> select * from sys.lob$ where lobj# in (24446,24448);
      OBJ#       COL#    INTCOL#      LOBJ#      PART#       IND#        TS#      FILE#     BLOCK#      CHUNK PCTVERSION$      FLAGS PROPERTY  RETENTION  FREEPOOLS     SPARE1     SPARE2 SPARE3
---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- ----------- ---------- -------- ---------- ---------- ---------- ---------- -------
     24445          3          3      24446          0      24447          4          0          0          1          10       1121     6146          4          0
     24445          4          4      24448          0      24449          4          0          0          1          10       1121     6146          4          0

SCOTT@test01p> SELECT COLUMN_NAME,pctversion, retention FROM user_lobs WHERE table_name='BLOG';
COLUMN_NAME          PCTVERSION  RETENTION
-------------------- ---------- ----------
TEXT
IMG
--//明顯12c dba_lobs檢視定義出了問題...

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