| From: | Dmitry Tkach <dmitry(at)openratings(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pg_general <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Weird query plan |
| Date: | 2003-09-17 20:33:29 |
| Message-ID: | 3F68C519.7050507@openratings.com |
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| Lists: | pgsql-general |
Tom Lane wrote:
>Dmitry Tkach <dmitry(at)openratings(dot)com> writes:
>
>
>>I now have the same problem with it, but the other way around - the
>>query with a condition on a runs quickly, and one with a condition on b
>>does not... and the query plans are the same, and have a as outer table...
>>
>>
>
>Hm. You know, I wonder whether the query plans really are the same.
>One of the reasons why 7.3 and later show the qual conditions is that
>it was too easy to fall into the trap of assuming that plans of the same
>structure had the same conditions. Try doing "explain verbose" and look
>to see if the plans look the same at that level of detail.
>
> regards, tom lane
>
>
I am afraid that's too much detail for me to look at :-)
I have no clue what all that stuff means :-(
But I am pretty sure they are the same - I did not know whether the
first one or the second was supposed to be the outer relation, so I
looked at it in the debugger...
So, I know that in both cases it was using b for the outer loop...
Thanks!
Dima
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