From: | Bruce Momjian <bruce(at)momjian(dot)us> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-committers(at)postgresql(dot)org |
Subject: | Re: pgsql: Eliminate some more O(N^2) behaviors in pg_dump/pg_restore. |
Date: | 2012-05-30 00:55:25 |
Message-ID: | 20120530005525.GM20260@momjian.us |
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Lists: | pgsql-committers |
On Tue, May 29, 2012 at 12:38:51AM +0000, Tom Lane wrote:
> Eliminate some more O(N^2) behaviors in pg_dump/pg_restore.
>
> This patch fixes three places (which AFAICT is all of them) where runtime
> was O(N^2) in the number of TOC entries, by using an index array to replace
> linear searches of the TOC list. This performance issue is a bit less bad
> than those recently fixed, because it depends on the number of items dumped
> not the number in the source database, so the problem can be dodged by
> doing partial dumps.
>
> The previous coding already had an instance of one of the two index arrays
> needed, but it was only calculated in parallel-restore cases; now we need
> it all the time. I also chose to move the arrays into the ArchiveHandle
> data structure, to make this code a bit more ready for the day that we
> try to sling multiple ArchiveHandles around in pg_dump or pg_restore.
>
> Since we still need some server-side work before pg_dump can really cope
> nicely with tens of thousands of tables, there's probably little point in
> back-patching.
Great, thanks. This will help speed up pg_upgrade.
--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ It's impossible for everything to be true. +
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