Tuning Oracle's Buffer Cache

Checking The Cache Hit Ratio

   SELECT (P1.value + P2.value - P3.value) / (P1.value + P2.value)
   FROM   v$sysstat P1, v$sysstat P2, v$sysstat P3
   WHERE  P1.name = 'db block gets'
   AND    P2.name = 'consistent gets'
   AND    P3.name = 'physical reads';


SELECT name, physical_reads, db_block_gets, consistent_gets,
       1 - (physical_reads / (db_block_gets + consistent_gets)) "Hit Ratio"


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