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pgsql: Fix O(N^2) behavior in pg_dump for large numbers of ownedsequen

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: pgsql-committers(at)postgresql(dot)org
Subject: pgsql: Fix O(N^2) behavior in pg_dump for large numbers of ownedsequen
Date: 2012-03-31 18:43:07
Message-ID: E1SE3GV-0000r1-77@gemulon.postgresql.org (view raw or flat)
Thread:
Lists: pgsql-committers
Fix O(N^2) behavior in pg_dump for large numbers of owned sequences.

The loop that matched owned sequences to their owning tables required time
proportional to number of owned sequences times number of tables; although
this work was only expended in selective-dump situations, which is probably
why the issue wasn't recognized long since.  Refactor slightly so that we
can perform this work after the index array for findTableByOid has been
set up, reducing the time to O(M log N).

Per gripe from Mike Roest.  Since this is a longstanding performance bug,
backpatch to all supported versions.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/0d8117abefdae69dbec7465adf2c68f5cd0412ac

Modified Files
--------------
src/bin/pg_dump/common.c  |    3 +++
src/bin/pg_dump/pg_dump.c |   41 +++++++++++++++++++++++------------------
src/bin/pg_dump/pg_dump.h |    1 +
3 files changed, 27 insertions(+), 18 deletions(-)

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Next:From: Tom LaneDate: 2012-03-31 19:51:57
Subject: pgsql: Fix O(N^2) behavior in pg_dump when many objects are independen
Previous:From: Tom LaneDate: 2012-03-31 17:17:12
Subject: Re: [COMMITTERS] pgsql: Add PGDLLIMPORT to ScanKeywords and NumScanKeywords.

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