Re: [RFC] pgstattuple/pgstatindex enhancement

On Tue, Feb 12, 2013 at 10:22 AM, Satoshi Nagayasu <snaga@uptime.jp> wrote:
> (1) Fix pgstatindex arguments to work same as pgstattuple.
>
> As the document describes, pgstattuple accepts 'schema.table'
> expression and oid of the table, but pgstatindex doesn't.
> (because I didn't add that when I created pgstatindex...)
>
> http://www.postgresql.org/docs/devel/static/pgstattuple.html
>
> So, I'd like to change pgstatindex arguments to allow
> schema name and oid.
>
> Does it make sense?

Not sure.  It seems nice, but it's also a backward-compatibility
break.  So I don't know.

> (2) Enhance pgstattuple/pgstatindex to allow block sampling.
>
> Now, we have large tables and indexes in PostgreSQL, and these are
> growing day by day.
>
> pgstattuple and pgstatindex are both very important to keep database
> performance well, but doing full-scans on large tables and indexes
> would generate big performance impact.
>
> So, now I think pgstattuple and pgstatindex should support
> 'block sampling' to collect block statistics with avoiding full-scans.
>
> With this block sampling feature, pgstattuple/pgstatindex would be
> able to collect block statistics from 1~10% of the blocks in the
> table/index if the table/index is large (maybe 10GB or more).

Now that sounds really nice.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company