Re: Re: [COMMITTERS] pgsql: Avoid extra locks in GetSnapshotData if old_snapshot_threshold < - Mailing list pgsql-hackers

From Kevin Grittner
Subject Re: Re: [COMMITTERS] pgsql: Avoid extra locks in GetSnapshotData if old_snapshot_threshold <
Date
Msg-id CACjxUsPeotFyOAaA84K0dexPJ3ucex-qBANd-0xoxUrzw+u+sQ@mail.gmail.com
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In response to Re: Re: [COMMITTERS] pgsql: Avoid extra locks in GetSnapshotData if old_snapshot_threshold <  (Alvaro Herrera <alvherre@2ndquadrant.com>)
List pgsql-hackers
On Wed, Jun 15, 2016 at 1:45 PM, Alvaro Herrera
<alvherre@2ndquadrant.com> wrote:

> Maybe it is possible to get into trouble if you're taking a sample for
> an expression index.

Maybe -- if you are using a function for an index expression which
does an explicit SELECT against some database table rather than
only using values from the row itself.  In such a case you would
have had to mark a function as IMMUTABLE which depends on table
contents.  I say you get to keep both pieces.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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