On Mon, Nov 10, 2008 at 2:42 PM, Lawrence, Ramon <[EMAIL PROTECTED]> wrote: > I have tested the Bloom filter patch. It compiles cleanly against HEAD.
Thank you for testing this! > As indicated, the performance improvements for hash join are good, > especially when the build table is filtered with a selection condition. > Performance improvements range from a couple of percent up to 20% for > multi-batch joins. Note that the bloom filter will slightly slow > queries where the filter has no benefit. I have a new patch which does not create a bloom filter unless it sees that the hash join is going to batch. I'll send it along later tonight. > I have not looked at the actual implementation of the Bloom filter, but > will proceed to do that next. One issue to be considered is how the > space used for the bloom filter is related to the work_mem allocated to > the join. That is, does the bloom filter consume some of the work_mem > space or is it treated as additional memory allocated to the join. Currently it's additional space not accounted for by work_mem. Additionally, it's a good amount more space than is required. This is fixed in the newer patch as well. -- Jonah H. Harris, Senior DBA myYearbook.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
