| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Bruce Momjian <bruce(at)momjian(dot)us> |
| Cc: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Peter Eisentraut <peter_e(at)gmx(dot)net>, Daniel Farina <daniel(at)heroku(dot)com>, Greg Stark <stark(at)mit(dot)edu>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: pg_upgrade and statistics |
| Date: | 2012-03-15 00:26:06 |
| Message-ID: | 9684.1331771166@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Bruce Momjian <bruce(at)momjian(dot)us> writes:
> Does anyone know how bad the queries will be with only one target?
Bad. That cycle seems like largely a waste of time. About the only
thing it would do for you is ensure that relpages/reltuples are up to
date, which seems like something we could possibly arrange for during
the data import.
> I did see if vacuumdb --analyze-only was somehow being throttled by the
> vacuum settings, but saw the drive at 100% utilization analying a 36GB
> table on a 24GB RAM server, so it seems I/O bound.
I think it'd be good to explicitly set vacuum_cost_delay to 0 in the
first pass, in the same way as you are forcing
default_statistics_target, just in case somebody has a nondefault
setting for that. The second pass could probably be allowed to use some
higher delay setting.
regards, tom lane
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