Saturday, 5 February 2011

Adjusting the Oracle Database 10g Shared Pool

<       media.techtarget.com/searchOracle/downloads/10g_shared_pool.doc

<        shared_pool_advice.sql

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set lines  100
set pages  999

column     c1     heading 'Pool |Size(M)'
column     c2     heading 'Size|Factor'
column     c3     heading 'Est|LC(M)  '
column     c4     heading 'Est LC|Mem. Obj.'
column     c5     heading 'Est|Time|Saved|(sec)'
column     c6     heading 'Est|Parse|Saved|Factor'
column     c7     heading 'Est|Object Hits'   format 999,999,999


SELECT
   shared_pool_size_for_estimate      c1,
   shared_pool_size_factor            c2,
   estd_lc_size                 c3,
   estd_lc_memory_objects             c4,
   estd_lc_time_saved                 c5,
   estd_lc_time_saved_factor          c6,
   estd_lc_memory_object_hits         c7
FROM
   v$shared_pool_advice;

                                                   Est        Est
                                                  Time      Parse
     Pool        Size        Est     Est LC      Saved      Saved          Est
   Size(M)     Factor    LC(M)    Mem. Obj.      (sec)     Factor  Object Hits
---------- ---------- ---------- ---------- ---------- ---------- ------------
        48         .5         48      20839    1459645          1  135,756,032
        64      .6667         63      28140    1459645          1  135,756,101
        80      .8333         78      35447    1459645          1  135,756,149
        96          1         93      43028    1459645          1  135,756,253
       112     1.1667        100      46755    1459646          1  135,756,842
       128     1.3333        100      46755    1459646          1  135,756,842
       144        1.5        100      46755    1459646          1  135,756,842
       160     1.6667        100      46755    1459646          1  135,756,842
       176     1.8333        100      46755    1459646          1  135,756,842
       192          2        100      46755    1459646          1  135,756,842

Here we see the statistics for the shared pool in a range from 50% of the current size to 200% of the current size.  These statistics can give you a great idea about the proper size for the shared_pool_size. 

If you are using AMM, Oracle Database 10g will adjust the shared_pool_size area with automated “alter system” commands, always ensuring that there is an optimal balance between the SGA RAM regions.

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