Re: Tweaking the planner's heuristics for small/empty tables

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Bruce Momjian <bruce(at)momjian(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Tweaking the planner's heuristics for small/empty tables
Date: 2011-07-13 21:16:05
Message-ID: 10706.1310591765@sss.pgh.pa.us
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Bruce Momjian <bruce(at)momjian(dot)us> writes:
> Tom Lane wrote:
>> Another reason not to rely completely on the auto-analyze update path is
>> that it doesn't work for temp tables, since autovac can't access another
>> session's temp tables. It's also worth noting that auto-analyze will
>> never kick in at all for tables of less than about 60 rows, unless there
>> is update/delete traffic on them.

> We could exclude temp tables in the 'if' test.

I considered whether to do things differently depending on the table's
temp status, but it's not clear what we could do better from knowing that.
If it's temp, it's more likely not less likely that we need some sort of
hack because vacuum/analyze won't come along to help.

regards, tom lane

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