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Re: Best way to get the latest revision from a table - Mailing list pgsql-performance

From Nikolas Everett
Subject Re: Best way to get the latest revision from a table
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Msg-id AANLkTikgQ8y4=5Ly_x+U0mQ7RRHprPGDd-rR8z1NOPWS@mail.gmail.com
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In response to Re: Best way to get the latest revision from a table  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
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Re: Best way to get the latest revision from a table
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On Fri, Jan 14, 2011 at 7:59 PM, Kevin Grittner <Kevin.Grittner@wicourts.gov> wrote:
Tom Lane <tgl@sss.pgh.pa.us> wrote:

> Shaun's example is a bit off

> As for speed, either one might be faster in a particular
> situation.

After fixing a mistake in my testing and learning from Tom's example
I generated queries against the OP's test data which produce
identical results, and I'm finding no significant difference between
run times for the two versions.  The OP should definitely try both
against the real tables.

<snip> 
-Kevin

After trying both against the real tables DISTINCT ON seems to be about two orders of magnitude faster than the other options.

Thanks so much!

Nik Everett

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