下面是我收藏的一些查找bad sql的方法:

    select * from (select buffer_gets, sql_text
    from v$sqlarea
    where buffer_gets > 500000
    order by buffer_gets desc) where rownum<=30;

    -- 執行次數多的SQL

    select sql_text,executions from
    (select sql_text,executions from v$sqlarea order by executions desc)
    where rownum<81;

    -- 讀硬盤多的SQL

    select sql_text,disk_reads from
    (select sql_text,disk_reads from v$sqlarea order by disk_reads desc)
    where rownum<21;

    -- 排序多的SQL

    select sql_text,sorts from
    (select sql_text,sorts from v$sqlarea order by sorts desc)
    where rownum<21;

    --分析的次數太多，執行的次數太少，要用綁變量的方法來寫sql

    set pagesize 600;
    set linesize 120;
    select substr(sql_text,1,80) "sql", count(*), sum(executions) "totexecs"
    from v$sqlarea
    where executions < 5
    group by substr(sql_text,1,80)
    having count(*) > 30
    order by 2;

    -- 游標的觀察

    set pages 300;
    select sum(a.value), b.name
    from v$sesstat a, v$statname b
    where a.statistic# = b.statistic#
    and b.name = 'opened cursors current'
    group by b.name;
    select count(0) from v$open_cursor;
    select user_name,sql_text,count(0) from v$open_cursor
    group by user_name,sql_text having count(0)>30;

    --查看當前用戶&username執行的SQL

   select sql_text from v$sqltext_with_newlines where (hash_value,address) in
    (select sql_hash_value,sql_address from v$session where username='&username')
    order by address,piece;

 

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