From: | "Greg Sabino Mullane" <greg(at)turnstep(dot)com> |
---|---|
To: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Better default_statistics_target |
Date: | 2008-06-13 00:55:46 |
Message-ID: | 8230f4174652fe68d79902f17a271afb@biglumber.com |
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Lists: | pgsql-hackers |
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> That was a pretty special case (LIKE/regex estimation), and we've since
> eliminated the threshold change in the LIKE/regex estimates anyway, so
> there's no longer any reason to pick 100 as opposed to any other number.
> So we're still back at "what's a good value and why?".
Glad to hear that, although I think this is only in HEAD, not backpatched,
right? Well at any rate, I withdraw my strong support for 100 and join in
the quest for a good number. The "anything but 10" campaign.
> I'm still concerned about the fact that eqjoinsel() is O(N^2). Show me
> some measurements demonstrating that a deep nest of equijoins doesn't
> get noticeably more expensive to plan --- preferably on a datatype with
> an expensive equality operator, eg numeric --- and I'm on board.
I hope someone else on the list can do this, because I can't. :)
- --
Greg Sabino Mullane greg(at)turnstep(dot)com
PGP Key: 0x14964AC8 200806122054
http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8
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