[20200129]子光標不共享BIND_EQUIV_FAILURE.txt

[20200129]子光標不共享BIND_EQUIV_FAILURE.txt

--//生產系統再次遇到大量BIND_EQUIV_FAILURE緣由致使子光標的狀況。我看了我之前測試遇到的狀況。
--//連接 http://blog.itpub.net/267265/viewspace-2156139/ =>[20180613]子光標不共享BIND_EQUIV_FAILURE。
--//別人曾經給我建議，問題可能出在alter session set statistics_level=all;的設置上，我也重複測試看看。

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

SYS@test> @ hide _cursor_obsolete_threshold
NAME                       DESCRIPTION                                     DEFAULT_VALUE SESSION_VALUE SYSTEM_VALUE ISSES ISSYS_MOD
-------------------------- ----------------------------------------------- ------------- ------------- ------------ ----- ---------
_cursor_obsolete_threshold Number of cursors per parent before obsoletion. TRUE          8192          8192         TRUE  FALSE

/*
grant execute on sys.dbms_lock to scott;

CREATE OR REPLACE FUNCTION sleep1 (seconds IN NUMBER)
RETURN NUMBER
is
d_date date;
BEGIN
  select sysdate into d_date from dual;
  sys.dbms_lock.sleep(seconds/10);
  RETURN seconds;
END;
/

CREATE OR REPLACE FUNCTION sleep (seconds IN NUMBER)
RETURN NUMBER
is
d_date date;
BEGIN
  select sysdate into d_date from dual;
--//sys.dbms_lock.sleep(0.01);
  RETURN seconds;
END;
/
*/
--//注：當時的測試由於別的緣由執行如上代碼，如今測試不須要。

create table t as select rownum id1,mod(rownum-1,1000)+1 id2 from dual connect by level<=2000;

SCOTT@test01p> select * from dba_extents where owner=user and segment_name='T'
  2  @ prxx
==============================
OWNER                         : SCOTT
SEGMENT_NAME                  : T
PARTITION_NAME                :
SEGMENT_TYPE                  : TABLE
TABLESPACE_NAME               : USERS
EXTENT_ID                     : 0
FILE_ID                       : 11
BLOCK_ID                      : 176
BYTES                         : 65536
BLOCKS                        : 8
RELATIVE_FNO                  : 11
PL/SQL procedure successfully completed.

2.創建測試腳本:
--//創建腳本by.txt,註解alter session set statistics_level=all;:
set term off
--//alter session set statistics_level=all;
variable x number;
exec :x := &&1;
SElect t.* from t where id2<=:x;
set term on
@ dpc '' ''
quit

--//創建shell腳本by.sh:
#!/bin/bash
# rm -f ez.txt
for i in $(seq 1000)
do
    sqlplus -s -l scott/btbtms@test01p @by.txt $i >> ez.txt
done
--//在家裏的筆記本上測試有點慢，減小循環到1000次。

3.測試：
--//執行腳本by.sh.
$ grep "SQL_ID" ez.txt |  uniq -c
   1000 SQL_ID  ckynkwp4t00rz, child number 0
--//能夠發現並無產生子光標。確實像別人講的那樣。

4.繼續測試:
--//修改腳本by.txt.取消註解alter session set statistics_level=all;.
set term off
alter session set statistics_level=all;
variable x number;
exec :x := &&1;
SElect t.* from t where id2<=:x;
set term on
@ dpc '' ''
quit

--//刷新共享池3次。
alter session set statistics_level=all;
alter session set statistics_level=all;
alter session set statistics_level=all;

$ mv ez.txt ezold.txt

--//執行腳本by.sh

$ grep "SQL_ID" ez.txt |  uniq -c
    500 SQL_ID  ckynkwp4t00rz, child number 0
     51 SQL_ID  ckynkwp4t00rz, child number 1
     56 SQL_ID  ckynkwp4t00rz, child number 2
     61 SQL_ID  ckynkwp4t00rz, child number 3
     67 SQL_ID  ckynkwp4t00rz, child number 4
     74 SQL_ID  ckynkwp4t00rz, child number 5
     81 SQL_ID  ckynkwp4t00rz, child number 6
     90 SQL_ID  ckynkwp4t00rz, child number 7
     20 SQL_ID  ckynkwp4t00rz, child number 8
--//在執行過程當中,能夠發現並出現大量子光標.

SCOTT@test01p> @ share ckynkwp4t00rz
old  15:           and q.sql_id like ''&1''',
new  15:           and q.sql_id like ''ckynkwp4t00rz''',
SQL_TEXT                       = SElect t.* from t where id2<=:x
SQL_ID                         = ckynkwp4t00rz
ADDRESS                        = 000007FF12B9AA10
CHILD_ADDRESS                  = 000007FF1265EDE8
CHILD_NUMBER                   = 0
LOAD_OPTIMIZER_STATS           = Y
REASON                         = <ChildNode><ChildNumber>0</ChildNumber><ID>39</ID><reason>Bind mismatch(25)</reason><size>0x0</size><details>extended_cursor_sharing</details></ChildNode>
--------------------------------------------------
SQL_TEXT                       = SElect t.* from t where id2<=:x
SQL_ID                         = ckynkwp4t00rz
ADDRESS                        = 000007FF12B9AA10
CHILD_ADDRESS                  = 000007FF16F0F400
CHILD_NUMBER                   = 1
REASON                         = <ChildNode><ChildNumber>1</ChildNumber><ID>39</ID><reason>Bind mismatch(33)</reason><size>1x4</size><init_ranges_in_first_pass>2540213050</init_ranges_in_first_pass></ChildNode>
--------------------------------------------------
SQL_TEXT                       = SElect t.* from t where id2<=:x
SQL_ID                         = ckynkwp4t00rz
ADDRESS                        = 000007FF12B9AA10
CHILD_ADDRESS                  = 000007FF13C989F8
CHILD_NUMBER                   = 2
BIND_EQUIV_FAILURE             = Y
REASON                         = <ChildNode><ChildNumber>2</ChildNumber><ID>39</ID><reason>Bind mismatch(33)</reason><size>1x4</size><init_ranges_in_first_pass>2841161709</init_ranges_in_first_pass></ChildNode>
--------------------------------------------------
...
--------------------------------------------------
SQL_TEXT                       = SElect t.* from t where id2<=:x
SQL_ID                         = ckynkwp4t00rz
ADDRESS                        = 000007FF12B9AA10
CHILD_ADDRESS                  = 000007FF13F41A10
CHILD_NUMBER                   = 8
BIND_EQUIV_FAILURE             = Y
REASON                         =
--------------------------------------------------
PL/SQL procedure successfully completed.

$ grep "SQL_ID" ez.txt |  uniq -c | awk '{ sum=sum+$1};END {print sum}'
1000
--//正好1000次。
--//能夠看出設置alter session set statistics_level=all;致使出現子光標不能共享，具體緣由是什麼不清楚。
--//我反覆測試屢次,結果都是同樣。

5.創建直方圖呢？

SCOTT@test01p> execute sys.dbms_stats.gather_table_stats ( OwnName => user,TabName => 't',Estimate_Percent => NULL,Method_Opt => 'FOR ALL COLUMNS SIZE 1024 ',Cascade => True ,No_Invalidate => false)
PL/SQL procedure successfully completed.
--//12c 能夠支持bucket大於254.

SCOTT@test01p> @ tab_lh scott t ''

DISPLAY TABLE_NAME OF COLUMN_NAME INFORMATION.
INPUT   OWNER TABLE_NAME COLUMN
SAMPLE  : @ TAB_LH TABLE_NAME [COLUMN_NAME]
IF NOT INPUT COLUMN_NAME ,USE "" .

COLUMN_NAME DATA_TYPE DATA_LENGTH N NUM_DISTINCT    DENSITY SAMPLE_SIZE TRANS_LOW TRANS_HIGH  NUM_NULLS NUM_BUCKETS LAST_ANALYZED       HISTOGRAM  DATA_DEFAULT
----------- --------- ----------- - ------------ ---------- ----------- --------- ---------- ---------- ----------- ------------------- ---------- -------------------------
ID1         NUMBER             22 Y         2000      .0005        2000 1         2000                0        1024 2020-01-29 19:44:04 HYBRID
ID2         NUMBER             22 Y         1000     .00025        2000 1         1000                0        1000 2020-01-29 19:44:04 FREQUENCY

--//刷新共享池3次。
alter session set statistics_level=all;
alter session set statistics_level=all;
alter session set statistics_level=all;

--//執行腳本by.txt。
set term off
--//alter session set statistics_level=all;
variable x number;
exec :x := &&1;
SElect t.* from t where id2<=:x;
set term on
@ dpc '' ''
quit

$ mv ez.txt ez17.txt
$ grep "SQL_ID" ez.txt |  uniq -c
   1000 SQL_ID  ckynkwp4t00rz, child number 0
--//沒有子光標產生。

SCOTT@test01p> execute sys.dbms_stats.gather_table_stats ( OwnName => user,TabName => 't',Estimate_Percent => NULL,Method_Opt => 'FOR ALL COLUMNS SIZE 254 ',Cascade => True ,No_Invalidate => false)
PL/SQL procedure successfully completed.

SCOTT@test01p> @ tab_lh scott t ''

DISPLAY TABLE_NAME OF COLUMN_NAME INFORMATION.
INPUT   OWNER TABLE_NAME COLUMN
SAMPLE  : @ TAB_LH TABLE_NAME [COLUMN_NAME]
IF NOT INPUT COLUMN_NAME ,USE "" .
COLUMN_NAME DATA_TYPE DATA_LENGTH N NUM_DISTINCT    DENSITY SAMPLE_SIZE TRANS_LOW TRANS_HIGH NUM_NULLS NUM_BUCKETS LAST_ANALYZED       HISTOGRAM DATA_DEFAULT
----------- --------- ----------- - ------------ ---------- ----------- --------- ---------- --------- ----------- ------------------- --------- ------------
ID1         NUMBER             22 Y         2000      .0005        2000 1         2000               0         254 2020-01-29 20:01:43 HYBRID
ID2         NUMBER             22 Y         1000       .001        2000 1         1000               0         254 2020-01-29 20:01:43 HYBRID

--//刷新共享池3次。
alter session set statistics_level=all;
alter session set statistics_level=all;
alter session set statistics_level=all;

$ mv ez.txt ez18.txt

$ grep "SQL_ID" ez.txt |  uniq -c
   1000 SQL_ID  ckynkwp4t00rz, child number 0
--//沒有子光標產生。
--//也就是與直方圖無關。

6.繼續測試：
--//取消直方圖設置。
SCOTT@test01p> execute sys.dbms_stats.gather_table_stats ( OwnName => user,TabName => 't',Estimate_Percent => NULL,Method_Opt => 'FOR ALL COLUMNS SIZE 1 ',Cascade => True ,No_Invalidate => false)
PL/SQL procedure successfully completed.

$ cat by.txt
set term off
alter session set statistics_level=all;
variable x number;
exec :x := &&1;
SElect t.* from t where id1<=:x;
set term on
@ dpc '' ''
quit

$ cat by.sh
#!/bin/bash
# rm -f ez.txt
for i in $(seq 2000 )
do
   sqlplus -s -l scott/btbtms@test01p @by.txt $i >> ez.txt
done

alter system flush shared_pool;

--//注意查新條件是id1<= :x,驗證在x=1000後是否出現子光標。

SCOTT@test01p> @ share basmuva6swhg4
SQL_TEXT                       = SElect t.* from t where id1<=:x
SQL_ID                         = basmuva6swhg4
ADDRESS                        = 000007FF1314E908
CHILD_ADDRESS                  = 000007FF13133298
CHILD_NUMBER                   = 0
LOAD_OPTIMIZER_STATS           = Y
REASON                         = <ChildNode><ChildNumber>0</ChildNumber><ID>39</ID><reason>Bind mismatch(25)</reason><size>0x0</size><details>extended_cursor_sharing</details></ChildNode>
--------------------------------------------------
SQL_TEXT                       = SElect t.* from t where id1<=:x
SQL_ID                         = basmuva6swhg4
ADDRESS                        = 000007FF1314E908
CHILD_ADDRESS                  = 000007FF13270B40
CHILD_NUMBER                   = 1
REASON                         = <ChildNode><ChildNumber>1</ChildNumber><ID>39</ID><reason>Bind mismatch(33)</reason><size>1x4</size><init_ranges_in_first_pass>3229815407</init_ranges_in_first_pass></ChildNode>
--------------------------------------------------
SQL_TEXT                       = SElect t.* from t where id1<=:x
SQL_ID                         = basmuva6swhg4
ADDRESS                        = 000007FF1314E908
CHILD_ADDRESS                  = 000007FF1343C4A0
CHILD_NUMBER                   = 2
BIND_EQUIV_FAILURE             = Y
REASON                         = <ChildNode><ChildNumber>2</ChildNumber><ID>39</ID><reason>Bind mismatch(33)</reason><size>1x4</size><init_ranges_in_first_pass>2954937500</init_ranges_in_first_pass></ChildNode>
..
PL/SQL procedure successfully completed.

$ grep "SQL_ID" ez.txt |  uniq -c
   1000 SQL_ID  basmuva6swhg4, child number 0
    101 SQL_ID  basmuva6swhg4, child number 1
    111 SQL_ID  basmuva6swhg4, child number 2
    122 SQL_ID  basmuva6swhg4, child number 3
    134 SQL_ID  basmuva6swhg4, child number 4
    147 SQL_ID  basmuva6swhg4, child number 5
    162 SQL_ID  basmuva6swhg4, child number 6
    178 SQL_ID  basmuva6swhg4, child number 7
     45 SQL_ID  basmuva6swhg4, child number 8

$ grep "SQL_ID" ez.txt |  uniq -c | awk 'BEGIN {a=909;} {sum=sum+$1;a=a*1.10;print  sum, a }'
1000 999.9
1101 1099.89
1212 1209.88
1334 1330.87
1468 1463.95
1615 1610.35
1777 1771.38
1955 1948.52
2000 2143.37

--//能夠看出一個規律返回1000條記錄是第1道坎，之後大約按照0.11的比例增長(最後一行測試不足不算)。固然這僅僅是個人猜想。

7.繼續測試：
--//翻轉執行看看，先執行2000：
$ cat by.sh
#!/bin/bash
# rm -f ez.txt
for i in $(seq 2000 -1 1 )
do
        sqlplus -s -l scott/btbtms@test01p @by.txt $i >> ez.txt
done

$ grep "SQL_ID" ez.txt |  uniq -c
   2000 SQL_ID  basmuva6swhg4, child number 0

--//並無產生子光標。