Diving Into the Shared Pool - An In Depth Look at Tuning the Shared Pool (Part 2) Oracle Tips by Mike Ault

Monitoring Library and Data Dictionary Caches

I've spent most of this article looking at the shared SQL area of the shared pool. Let's wrap up with a high level look at the library and data dictionary caches. The library cache area is monitored via the V$LIBRARYCACHE view and contains the SQL area, PL/SQL area, table, index and cluster cache areas. The data dictionary caches contain cache area for all data dictionary related definitions.

The script in Figure 9 creates a report on the library caches. The items of particular interest in the report generated by the script in Figure 9 (shown in Figure 10) are the various ratios.

rem

rem Title: libcache.sql

rem

rem FUNCTION: Generate a library cache report

rem

column namespace                        heading "Library Object"

column gets             format 9,999,999 heading "Gets"

column gethitratio      format 999.99   heading "Get Hit%"

column pins             format 9,999,999 heading "Pins"

column pinhitratio      format 999.99   heading "Pin Hit%"

column reloads          format 99,999   heading "Reloads"

column invalidations    format 99,999   heading  "Invalid"

column db format a10

set pages 58 lines 80

start title80 "Library Caches Report"

define output = rep_out\&db\lib_cache

spool &output

select
 

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For more information on this topic, I recommend Don Burleson's latest book "Oracle Tuning: The Definitive Reference".  You can buy it direct from the publisher for 50%-off and get instant access to the code depot of Oracle tuning scripts:

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