Thank you for the detailed explanation.
Regards,
Jayadevan
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Jayadevan M wrote:
It is mentioned that table data blocks have data about tuple visibility and hence table scans
are always necessary. So how does PostgreSQL reduce the number of blocks
to be read by using indexes?
To be useful, a query utilizing an index must be selective: it must
only retu
Hello,
> PostgreSQL can't currently avoid reading the table, because that's
> where the tuple visibility information is stored. We've been making
> progress toward having some way to avoid reading the table for all
> except very recently written tuples, but we're not there yet (in any
> production
> PostgreSQL can't currently avoid reading the table, because that's
> where the tuple visibility information is stored. We've been making
> progress toward having some way to avoid reading the table for all
> except very recently written tuples, but we're not there yet (in any
> production versio
check the undo logs to
determine the state that applies to your transaction. Its just two different
ways to accomplish the same thing.
Bob Lunney
--- On Fri, 6/11/10, Jayadevan M wrote:
> From: Jayadevan M
> Subject: [PERFORM] Query about index usage
> To: pgsql-performance@postgre
Jayadevan M wrote:
One query about PostgreSQL's index usage. If I select just one column on
which there is an index (or select only columns on which there is an
index), and the index is used by PostgreSQL, does PostgreSQL avoid table
access if possible?
PostgreSQL keeps information about what
Jayadevan M wrote:
> One query about PostgreSQL's index usage. If I select just one
> column on which there is an index (or select only columns on which
> there is an index), and the index is used by PostgreSQL, does
> PostgreSQL avoid table access if possible?
PostgreSQL can't currently avoid
Hello all,
One query about PostgreSQL's index usage. If I select just one column on
which there is an index (or select only columns on which there is an
index), and the index is used by PostgreSQL, does PostgreSQL avoid table
access if possible? I am trying to understand the differences betwee
