DBA Tips Archive for Oracle

  


Tuning the Shared Pool

by Jeff Hunter, Sr. Database Administrator

The following SQL script produces a report that will help the DBA to tune the Shared Pool. It produces a report on the library cache hits and misses.

  rem library.sql - lists the library cache
  prompt
  prompt         ========================= 
  prompt         LIBRARY CACHE MISS RATIO
  prompt         ========================= 
  prompt (If > 1 then increase the shared_pool_size in init.ora)
  prompt
  column "LIBRARY CACHE MISS RATIO" format 99.9999
  column "executions"    format 999,999,999
  column "Cache misses while executing"    format 999,999,999
  select sum(pins) "executions", sum(reloads) "Cache misses while executing",
      (((sum(reloads)/sum(pins)))) "LIBRARY CACHE MISS RATIO"
  from v$librarycache; 
   
  prompt
  prompt         ========================= 
  prompt          Library Cache Section
  prompt         ========================= 
  prompt hit ratio should be > 70, and pin ratio > 70 ...
  prompt

  column "reloads" format 999,999,999
  select namespace, trunc(gethitratio * 100) "Hit ratio",
  trunc(pinhitratio * 100) "pin hit ratio", reloads "reloads"
  from v$librarycache;


  Sample Output
  -------------
  NAMESPACE       Hit ratio pin hit ratio      reloads
  --------------- --------- ------------- ------------
  SQL AREA               98            98            7
  TABLE/PROCEDURE        79            50            0
  BODY                   54            50            0
  TRIGGER                 0             0            0
  INDEX                   0             0            0
  CLUSTER                96            97            0
  OBJECT                100           100            0
  PIPE                  100           100            0

  8 rows selected.


Copyright (c) 1998-2017 Jeffrey M. Hunter. All rights reserved.

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Last modified on
Tuesday, 06-Apr-1999 00:00:00 EDT
Page Count: 17832