| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Gregory Stark <stark(at)enterprisedb(dot)com> |
| Cc: | tmp <skrald(at)amossen(dot)dk>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Optimizing DISTINCT with LIMIT |
| Date: | 2008-12-08 16:26:15 |
| Message-ID: | 27036.1228753575@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Gregory Stark <stark(at)enterprisedb(dot)com> writes:
> But I can also see Tom's reluctance. It's a fair increase in the amount of
> code to maintain in that file for a pretty narrow use case. On the other hand
> it looks like it would be all in that file. The planner wouldn't have to do
> anything special to set it up which is nice.
No, the planner would have to be changed to be aware of the behavioral
difference. Otherwise it might pick some other plan besides the one
that has the performance advantage.
regards, tom lane
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