| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Planner creating ineffective plans on LEFT OUTER joins |
| Date: | 2008-06-26 16:57:38 |
| Message-ID: | 17868.1214499458@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> On Thu, 2008-06-26 at 12:36 -0400, Robert Haas wrote:
>> It's my understanding that the philosophy of the PGDG in the past has
>> been to avoid putting any kind of hints into the system, focusing
>> rather an improving the planning of queries.
> It's not a specific hint, its a general goal setting.
Right. There are definitely places where we've made engineering
judgements to not attempt a particular type of optimization because it'd
be too expensive compared to the typical payoff. Simon's idea has some
merit for providing a framework to deal with that type of situation.
However, just adding a GUC variable isn't going to make anything happen
--- we'd need some concrete plans about what we'd do with it.
regards, tom lane
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