| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Gregory Stark <stark(at)enterprisedb(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, "jd(at)commandprompt(dot)com" <jd(at)commandprompt(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Greg Smith <gsmith(at)gregsmith(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: benchmarking the query planner |
| Date: | 2008-12-12 18:22:20 |
| Message-ID: | 1229106140.8673.80.camel@ebony.2ndQuadrant |
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| Lists: | pgsql-hackers |
On Fri, 2008-12-12 at 13:10 -0500, Tom Lane wrote:
> If we don't
> have at least ballpark-correct figures for cost and number of output
> rows, we'll start making mistakes at higher plan levels.
That's definitely where we are now.
Had a call with a customer today where I said "it's OK, its only out by
3 orders of magnitude, it gets worse than that". 9 hour query, with
substantially incorrect EXPLAIN.
I don't claim to have any/all of the answers myself, but this needs
attention very badly.
--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Training, Services and Support
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