| From: | Steve Clark <sclark(at)netwolves(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Richard Broersma <richard(dot)broersma(at)gmail(dot)com>, Ivan Sergio Borgonovo <mail(at)webthatworks(dot)it>, PostgreSQL <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: MERGE: performance advices |
| Date: | 2008-09-02 18:16:29 |
| Message-ID: | 48BD82FD.9000609@netwolves.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
Tom Lane wrote:
> "Richard Broersma" <richard(dot)broersma(at)gmail(dot)com> writes:
>
>>There is one possible alteration that may or many not improve
>>performance. This would be to replace the EXISTS with a LEFT JOIN
>>WHERE IS NOT NULL;
>
>
> That changes the behavior, doesn't it? Or is event_log_no a unique
> key for Myevents? I think what you want is to make the EXISTS an IN
> instead.
>
> regards, tom lane
>
>
Yes event_log_no is a unique key for myevents.
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