Hi, 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 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. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
