Re: 9.4 release notes

On Sun, May 4, 2014 at 6:49 AM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> + <listitem>
> + <para>
> + Have pg_stat_statements use a flat file for query text storage, allowing higher limits (Peter Geoghegan)
> + </para>
> +
> + <para>
> + Also add the ability to retrieve all pg_stat_statements information except the query text. This allows programs to reuse the query
> + text already retrieved by referencing queryid.
> + </para>
> + </listitem>
>
> This isn't an optional thing, is it?

This is intended to be used by time-series monitoring tools that
aggregate and graph pg_stat_statements data temporally. They usually
won't need query texts, and so can only retrieve them lazily. The
pg_stat_statements view presents exactly the same interface for ad-hoc
querying, though.

The point of the first item is that there is no longer *any*
limitation on the size of stored query texts. They are no longer
truncated to track_activity_query_size bytes. The shared memory
overhead is also decreased substantially, allowing us to increase the
default pg_stat_statements.max setting from 1,000 to 5,000, while
still reducing the overall shared memory overhead (assuming a default
track_activity_query_size). I think that the removal of the
limitation, and the substantial lowering of the per-entry footprint
should both be explicitly noted.

--
Peter Geoghegan