Re: Consistent gets

Anjo,

Why do they appear in the first place?

Jared

Anjo Kolk <anjo_at_oraperf.com>
Sent by: root_at_fatcity.com
 10/09/2002 09:09 AM
 Please respond to ORACLE-L  

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
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        Subject:        Re: Consistent gets

No problem as long as the stat "no work - consistent read gets" (v$sysstat) is also close to that number.

Anjo.

Stephane Faroult wrote:
>
> Has anybody any idea why a query against tables on which very few if any
update are applied would display a high number of consistent gets ?
> Details : Big query involving 4/5 tables, most of them partitioned. This
is a test database, db block buffers about 100M, 5,000,000 of logical reads with 8K blocks which means that the SGA is flushed a number of times. The execution plan starts with a partition scan, then a series of nested loops (hash join disappointing). The number of db block gets corresponds to the number of blocks read during the partition scan; everything else appears as consistent gets. You can rule out delayed cleanout, since the same behaviour is displayed when the same query is run over and over and not update at all takes place. Another curious symptom is that the number of rows returned per second decreases by a factor 3 or 4 between the beginning and the end of the query. Believe me, no hideous hidden scan of table of partition.
>
> TIA,
>
> Stephane Faroult
> Oriole
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