cursor：mutex S事件查看

1.查看version_count大于500的sql_id

select sql_id,version_count from v$sqlarea where version_count> 500 order by 2 desc;

SQL_ID        VERSION_COUNT
------------- -------------
50u4uqg9vjk78           1705

2.查看sql的子游标个数

select count(CHILD_NUMBER) from v$sql_shared_cursor where sql_id='50u4uqg9vjk78';

COUNT(CHILD_NUMBER)
-------------------
                935

3.查看sql游标不能共享的原因

select * from v$sql_shared_cursor where sql_id='50u4uqg9vjk78' and rownum<10;

select child_number,optimizer_mismatch,optimizer_mode_mismatch from v$sql_shared_cursor where sql_id='50u4uqg9vjk78' and rownum<10;

4.查看sql占用内存大小

SELECT SUM (sharable_mem) / 1024 / 1024 || 'M' FROM v$sqlarea where sql_id='50u4uqg9vjk78';

SUM(SHARABLE_MEM)/1024/