| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Nathan Wagner <nw+pg(at)hydaspes(dot)if(dot)org>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: patch for geqo tweaks |
| Date: | 2015-11-04 18:29:18 |
| Message-ID: | 20151104182918.GS6104@alvherre.pgsql |
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| Lists: | pgsql-hackers |
Tom Lane wrote:
> Having said that, though, I believe that it's also probably a
> *different* initial shuffle, which may well mean that GEQO gives
> different plans in some cases. That doesn't bother me as long as
> we only make the change in HEAD, but does anyone want to complain?
Uh, do we promise that plans found by geqo are stable? That would seem
odd to me -- wouldn't they change shape on a whim, say because the stats
are different? It seems odd to look for plan stability using a genetic
algorithm.
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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