Pete Stevenson wrote: > Maybe I could figure out the lines of code that add versions into a > table and then those that collect old versions (they do get collected, > right?). Anyway, thought being I could profile while running TPC-C or > similar. I was hoping that someone might be able to jump on this with > a response that they already did something similar.
Old tuple versions are "collected" (removed) by either vacuum (see vacuumlazy.c) and heap_page_prune. The latter is one thing that could perhaps somehow be offloaded, as it's quite independent from the other stuff. You can prune removable tuples at no additional cost from an unlocked dirty page, which is a useful optimization because then client-connected backends don't need to prune them later. -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers