[20180914]oracle 12c 表 full_hash_value如何計算.txt

--//昨天在12c下看表full_hash_value與11g的full_hash_value不同,不過12c使用pdb,猜測跟PDB有關.
--//通過測試說明問題.

1.環境:
SCOTT@book> @ &r/ver1
PORT_STRING??????????????????? VERSION??????? BANNER
------------------------------ -------------- --------------------------------------------------------------------------------
x86_64/Linux 2.4.xx??????????? 11.2.0.4.0???? Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

SCOTT@book> select owner,name,namespace,type,hash_value,full_hash_value from V$DB_OBJECT_CACHE where owner='SCOTT' and name='EMP';
OWNER? NAME NAMESPACE?????? TYPE? HASH_VALUE FULL_HASH_VALUE
------ ---- --------------- ----- ---------- --------------------------------
SCOTT? EMP? TABLE/PROCEDURE TABLE 3800164305 684ea11e3eab602b778e1dd1e281e7d1

--//以上11g的結果.
$ echo -e -n "EMP.SCOTT\01\0\0\0" | md5sum |sed 's/? -//' | xxd -r -p | od -t x4 | sed? -n? -e 's/^0000000 //' -e 's/ //gp'
684ea11e3eab602b778e1dd1e281e7d1

2.而在12c下:

SCOTT@test01p> @ ver1
PORT_STRING??????????????????? VERSION??????? BANNER?????????????????????????????????????????????????????????????????????????????? CON_ID
------------------------------ -------------- -------------------------------------------------------------------------------- ----------
IBMPC/WIN_NT64-9.1.0?????????? 12.1.0.1.0???? Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production????????????? 0

SCOTT@test01p> select owner,name,namespace,type,hash_value,full_hash_value,con_id,con_name from V$DB_OBJECT_CACHE where owner='SCOTT' and name='EMP';
OWNER??????????????? NAME???????????????? NAMESPACE??????????? TYPE???????????????? HASH_VALUE FULL_HASH_VALUE????????????????????? CON_ID CON_NAME
-------------------- -------------------- -------------------- -------------------- ---------- -------------------------------- ---------- --------------------
SCOTT??????????????? EMP????????????????? TABLE/PROCEDURE????? TABLE??????????????? 1676251406 5675b61ea54d0cd0370c43ab63e9910e????????? 3 TEST01P

--//對比前面可以發現FULL_HASH_VALUE不一樣,也很容易猜測12c 的FULL_HASH_VALUE計算加入CON_NAME的內容.
D:\tools\rlwrap>D:\tools\linux\usr\local\wbin\echo -e -n "EMP.SCOTT.TEST01P\01\0\0\0" | md5sum |sed "s/? -//" | D:\tools\Vim\vim80\xxd -r -p | od -t x4 | sed? -n? -e "s/^0000000 //" -e "s/ //gp"
5675b61ea54d0cd0370c43ab63e9910e

--//OK,能對上.
--//注:windows要安裝unxutil包.echo不能使用windows下的echo.必須使用ubxutil包的echo(該命令支持-n -e參數)
--//sed 命令格式要使用雙引號.
--//我個人還使用vim自帶的xxd.

--//可以發現12c計算表的full_hash_value是 計算table_name.owner_name.con_name\01\0\0\0的md5sum值.

3.從以上測試可以聯想到的問題就是后面都是補"\01\0\0\0",為什么呢?
--//很容易聯想到namespace

SYS@test> select distinct kglhdnsp,kglhdnsd,kglobtyd from x$kglob order by 1;
KGLHDNSP KGLHDNSD?????????????????????? KGLOBTYD
-------- ------------------------------ -------------------
?????? 0 SQL AREA?????????????????????? CURSOR
?????? 1 TABLE/PROCEDURE??????????????? CURSOR
?????? 1 TABLE/PROCEDURE??????????????? FUNCTION
?????? 1 TABLE/PROCEDURE??????????????? LIBRARY
?????? 1 TABLE/PROCEDURE??????????????? OPERATOR
?????? 1 TABLE/PROCEDURE??????????????? PACKAGE
?????? 1 TABLE/PROCEDURE??????????????? PROCEDURE
?????? 1 TABLE/PROCEDURE??????????????? SCHEDULER CLASS
?????? 1 TABLE/PROCEDURE??????????????? SCHEDULER JOB
?????? 1 TABLE/PROCEDURE??????????????? SCHEDULER PROGRAM
?????? 1 TABLE/PROCEDURE??????????????? SCHEDULER SCHEDULE
?????? 1 TABLE/PROCEDURE??????????????? SCHEDULER WINDOW
?????? 1 TABLE/PROCEDURE??????????????? SEQUENCE
?????? 1 TABLE/PROCEDURE??????????????? SYNONYM
?????? 1 TABLE/PROCEDURE??????????????? TABLE
?????? 1 TABLE/PROCEDURE??????????????? TYPE
?????? 1 TABLE/PROCEDURE??????????????? VIEW
?????? 2 BODY?????????????????????????? CURSOR
?????? 2 BODY?????????????????????????? PACKAGE BODY
?????? 3 TRIGGER??????????????????????? TRIGGER
?????? 4 INDEX????????????????????????? INDEX
?????? 5 CLUSTER??????????????????????? CLUSTER
?????? 5 CLUSTER??????????????????????? CURSOR
????? 10 QUEUE????????????????????????? QUEUE
????? 18 PUB SUB INTERNAL INFORMATION?? PUB SUB INTERNAL INFORMATION
????? 23 RULESET??????????????????????? RULESET
????? 24 RESOURCE MANAGER?????????????? RESOURCE MANAGER CONSUMER GROUP
????? 24 RESOURCE MANAGER?????????????? RESOURCE MANAGER PLAN
????? 28 SUBSCRIPTION?????????????????? SUBSCRIPTION
????? 38 RULE EVALUATION CONTEXT??????? RULE EVALUATION CONTEXT
????? 45 MULTI-VERSION OBJECT FOR TABLE CURSOR
????? 45 MULTI-VERSION OBJECT FOR TABLE MULTI-VERSIONED OBJECT
????? 48 MULTI-VERSION OBJECT FOR INDEX CURSOR
????? 48 MULTI-VERSION OBJECT FOR INDEX MULTI-VERSIONED OBJECT
????? 51 SCHEDULER GLOBAL ATTRIBUTE???? CURSOR
????? 51 SCHEDULER GLOBAL ATTRIBUTE???? SCHEDULER GLOBAL ATTRIBUTE
????? 52 RESOURCE MANAGER CDB?????????? RESOURCE MANAGER CDB PLAN
????? 64 EDITION??????????????????????? EDITION
????? 69 DBLINK???????????????????????? CURSOR
????? 72 OBJECT ID????????????????????? OBJECT ID
????? 73 SCHEMA???????????????????????? CURSOR
????? 73 SCHEMA???????????????????????? NONE
????? 74 DBINSTANCE???????????????????? CURSOR
????? 75 SQL AREA STATS???????????????? CURSOR STATS
????? 79 ACCOUNT_STATUS???????????????? NONE
????? 82 SQL AREA BUILD???????????????? CURSOR
????? 88 PDB??????????????????????????? CURSOR
????? 88 PDB??????????????????????????? PDB
????? 93 AUDIT POLICY?????????????????? AUDIT POLICY
???? 103 OPTIMIZER FINDING????????????? Optimizer Finding
???? 104 OPTIMIZER DIRECTIVE OWNER????? CURSOR
???? 104 OPTIMIZER DIRECTIVE OWNER????? Optimizer Directive Owner
???? 113 GTT SESSION PRIVATE STATS????? CURSOR
???? 125 PDBOPER??????????????????????? CURSOR
54 rows selected.

--//比如你就不能建立emp的sequence.
SCOTT@test01p> create sequence emp cache 100;
create sequence emp cache 100
??????????????? *
ERROR at line 1:
ORA-00955: name is already used by an existing object

4.SQL語句的full_hash_value(sql_id)計算還是和以前一樣計算 sql文本\0(不包括分號) md5sum值.
--//這樣帶來一個問題,就是如果不同pdb下的語句如果一樣,由于文本內容一樣,這樣計算的sql_id一樣,導致出現大量子光標.

轉載于:https://www.cnblogs.com/lfree/p/9649165.html

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