On 2015-01-16 12:15:35 -0500, Tom Lane wrote: > Andres Freund <and...@2ndquadrant.com> writes: > > On 2014-12-25 01:26:53 +1300, David Rowley wrote: > >> So I think v3 is the one to go with, and I can't see any problems with it, > >> so I'm marking it as ready for committer. > > > And committed. > > It strikes me that this patch leaves some lookups on the table, > specifically that it fails to avoid repeated hash_search lookups > inside tbm_page_is_lossy() in the situation where we're adding > new TIDs to an already-lossified page. Is it worth adding a few > more lines to handle that case as well?
There was a alternative version (v2.3 in 549950fb.2050...@sigaev.ru) of the patch that cached the lossyness of a page, but Teodor/David didn't find it to be beneficial in their benchmarking. Teodor's argument was basically that it's completely lost in the noise due to the much bigger overhead of rechecks. I thought it'd better to get this improvement committed rather than waiting for someone to find a even bigger improvement for some case. 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
