On Mon, May 5, 2014 at 2:13 PM, Andres Freund <and...@2ndquadrant.com> wrote: > On 2014-05-05 13:52:39 -0400, Robert Haas wrote: >> Today, I discovered that when building a btree index, the btree code >> uses index_form_tuple() to create an index tuple from the heap tuple, >> calls tuplesort_putindextuple() to copy that tuple into the sort's >> memory context, and then frees the original one it built. This seemed >> inefficient, so I wrote a patch to eliminate the tuple copying. It >> works by adding a function tuplesort_putindextuplevalues(), which >> builds the tuple in the sort's memory context and thus avoids the need >> for a separate copy. I'm not sure if that's the best approach, but >> the optimization seems wortwhile. > > Hm. It looks like we could quite easily just get rid of > tuplesort_putindextuple(). The hash usage doesn't look hard to convert.
I glanced at that, but it wasn't obvious to me how to convert the hash usage. If you have an idea, I'm all ears. >> I tested it by repeatedly executing "REINDEX INDEX >> pgbench_accounts_pkey" on a PPC64 machine. pgbench_accounts contains >> 10 million records. With unpatched master as of >> b2f7bd72c4d3e80065725c72e85778d5f4bdfd4a, I got times of 6.159s, >> 6.177s, and 6.201s. With the attached patch, I got times of 5.787s, >> 5.972s, and 5.913s, a savings of almost 5%. Not bad considering the >> amount of work involved. > > Yes, that's certainly worthwile. Nice. Thanks. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers