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存档于 六月, 2006

cursor_sharing = similar

作者：admin 发表时间：六月 - 6 - 2006

我们先看看在表没有分析无统计数据情况下的表现 

SQL> alter session set cursor_sharing = similar; 
  
Session altered.


SQL> select name,value from v$sysstat where name like ‘%parse%’; 
  
NAME                                                                  VALUE 
—————————————————————- ———- 
parse time cpu                                                         4948 
parse time elapsed                                                     4468 
parse count (total)                                                  170148 
parse count (hard)                                                     1619  (硬分析次数)
parse count (failures)                                                   80 
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类别：Oracle

imp时遇到imp 3 imp 17 ora6650错误

作者：admin 发表时间：六月 - 5 - 2006

IMP-00017: 由于 ORACLE 的 6550 错误，以下的语句失败

 ”DECLARE  SREC DBMS_STATS.STATREC; BEGIN SREC.MINVAL := ‘3238453435363030363″

 ”642423131443841314237303030433736343937414631′; SREC.MAXVAL := ‘32384534353″

 ”63031363642423131443841314237303030433736343937414631′; SREC.EAVS := 4; SRE”

 ”C.CHVALS := DBMS_STATS.CHARARRAY(DECLARE  SREC DBMS_STATS.STATREC; BEGIN SR”

 ”EC.MINVAL := ‘3238453435363030363642423131443841314237303030433736343937414″

 ”631′; SREC.MAXVAL := ‘32384534353630313636424231314438413142373030304337363″

 ”43937414631′; SREC.EAVS := 4; SREC.CHVALS := DBMS_STATS.CHARARRAY(,垚); ”

 ”SREC.NOVALS := DBMS_STATS.NUMARRAY(260756140765309000000000000000000000,260″

 ”756140765309000000000000000000000); SREC.BKVALS := DBMS_STATS.NUMARRAY(0,1)”

 ”; SREC.EPC := 2; DBMS_STATS.SET_COLUMN_STATS(NULL,’”ASSET_TAPE”‘,’”SORT_ID”"

 ”‘, NULL ,NULL,NULL,2,.1,0,srec,33,2); END;”

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类别：Oracle

返回了一行，为何card不为1？

作者：admin 发表时间：六月 - 5 - 2006

ops$tkyte@ORA920> select * from t where object_id = 55;

 

Execution Plan

———————————————————-

   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=3 Card=13 Bytes=96)

   1    0   TABLE ACCESS (BY INDEX ROWID) OF ‘T’ (Cost=3 Card=13 Bytes=96)

   2    1     INDEX (RANGE SCAN) OF ‘T_IDX’ (NON-UNIQUE) (Cost=13 Card=1)

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类别：Oracle