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Sorting Performance Improvement for Postgres 9.2

Bruce Momjian2/16/2012

As part of the work on Postgres 9.2, yesterday Robert Haas applied a much-discussed (December, January, February) patch by Peter Geoghegan to improve sort performance. Having recently blogged about how work_mem affects sort performance, I thought I would re-run my tests to see the improvement:



   Temporary Storage   |   Old  |   New
magnetic               |    68  |    67
magnetic (writeback)   |    50  |    48
SSD                    |    36  |    32
tmpfs                  |    30  |    27
none (high work_mem)   |    12  |     9.5



As you can see, the new patch shaves about 3 seconds off of my test. That isn't a huge win for sorts that have to hit the disk, but for in-memory sorts (the last row), it yields a 20% improvement, which closely matches the ~25% reported by testers of the patch. This is one of the many sort improvements coming in Postgres 9.2.

Bruce Momjian is a co-founder of the PostgreSQL Global Development Group, and has worked on PostgreSQL since 1996 as a committer and community leader. He is a frequent speaker and Postgres evangelist and travels worldwide appearing at conferences to help educate the community on the business value o ...