From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Jim Nasby <decibel(at)decibel(dot)org> |
Cc: | pgsql-hackers(at)postgreSQL(dot)org |
Subject: | Re: Effects of GUC settings on automatic replans |
Date: | 2007-04-09 20:59:17 |
Message-ID: | 10551.1176152357@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Jim Nasby <decibel(at)decibel(dot)org> writes:
> On Mar 25, 2007, at 12:31 PM, Tom Lane wrote:
>> The other argument was that you might not want the costs of searching
>> for contradictory constraints if your workload was such that the
>> search
>> never or hardly ever succeeds. That still justifies the existence of
>> this GUC variable, I think, but I don't see that it's a reason to
>> force
>> replanning if the variable is changed. Certainly it's not any more
>> interesting than any of the other variables affecting planner
>> behavior.
> I'm doubtful that there are any cases where not doing the search
> would be worth the time saved, since it'd mean you'd be getting data
> out of most/all partitions at that point...
You've got some kind of blinders on, Jim ... queries against large
partitioned tables are not the only ones in the world, or even most
of them.
regards, tom lane
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