Re: Trying to understand why a query is filtering when there is a composite index - Mailing list pgsql-performance

From Tom Lane
Subject Re: Trying to understand why a query is filtering when there is a composite index
Date
Msg-id 1434438.1724111726@sss.pgh.pa.us
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In response to Re: Trying to understand why a query is filtering when there is a composite index  ("Stephen Samuel (Sam)" <sam@sksamuel.com>)
Responses Re: Trying to understand why a query is filtering when there is a composite index
List pgsql-performance
"Stephen Samuel (Sam)" <sam@sksamuel.com> writes:
> This index covers both columns needed in the predicate/projection, and the
> visibility bit is almost always set, why does it need to go to the heap at
> all and doesn't just get what it needs from the index?

Peter's theory was that the particular tuples you were fetching were
in not-all-visible pages.  That seems plausible to me.

            regards, tom lane



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