[20181122]了解数据库缓存被那些对象占用.txt

--//没事,随手写一个脚本,看看数据库缓存被那些对象占用:

column object_name format a30

column owner format a20

column number_MB format 99999999.99

SELECT *

  FROM (  SELECT o.owner,

                 o.object_name,

                 COUNT (*) number_of_blocks,

                 COUNT (DISTINCT FILE# || '.' || BLOCK#) distinct_block_count,

sum (decode(dirty,'Y',1,0)) dirty_block,

                 COUNT (*) - COUNT (DISTINCT FILE# || '.' || BLOCK#)

                    diff_number_block,

                 ROUND (COUNT (*) * 8 / 1024, 2) number_Mb, ROUND ( (ratio_to_report (SUM (1)) OVER () * 100),2) rr

            FROM dba_objects o, v$bh v

           WHERE o.data_object_id = v.objd AND o.owner != 'SYS' and v.status <> 'free'

        GROUP BY o.owner, o.object_name

        ORDER BY COUNT (*) DESC)

 WHERE ROWNUM <= 50;

--//我直接按照8k数据块计算.取前50个对象.

--//顺便提一下,对于cluster table对象无效.不过一般应用很少应用这种类型的表.

--//把条件o.owner != 'SYS'改写成o.owner = 'SYS',就明白什么回事.

column object_name format a30

column owner format a20

column number_MB format 99999999.99

SELECT *

  FROM (  SELECT o.owner,

                 o.object_name,

                 v.objd,

                 COUNT (*) number_of_blocks,

                 COUNT (DISTINCT FILE# || '.' || BLOCK#) distinct_block_count,

                 sum (decode(dirty,'Y',1,0)) dirty_block,

                 COUNT (*) - COUNT (DISTINCT FILE# || '.' || BLOCK#)

                    diff_number_block,

                 ROUND (COUNT (*) * 8 / 1024, 2) number_Mb, ROUND ( (ratio_to_report (SUM (1)) OVER () * 100),2) rr

            FROM dba_objects o, v$bh v

           WHERE o.data_object_id = v.objd AND o.owner = 'SYS' and v.status <> 'free'

        GROUP BY o.owner, o.object_name,v.objd

        ORDER BY COUNT (*) DESC)

 WHERE ROWNUM <= 50;

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