On 2011-11-30 21:58, Robert Haas wrote:
The row-count estimates look reasonably accurate, so there's some other problem here. What do you have random_page_cost, seq_page_cost, and effective_cache_size set to? You might try "SET random_page_cost=2" or even "SET random_page_cost=0.5; SET seq_page_cost=0.3" and see if those settings help
I may be seing ghosts here, since I've encountered the same problem. But the Query-planner does not take toast into account, so a Sequential Scan + filter only cost what it takes to scan the main table, but fts-fields are typically large enough to be toasted so the cost should be main+toast (amount of pages) + filtering cost. I posted about it yesterday: http://archives.postgresql.org/pgsql-hackers/2011-11/msg01754.php If above problem is on <9.1 a patch to proper account of gin-estimates have been added to 9.1 which also may benefit the planning: http://www.postgresql.org/docs/9.1/static/release-9-1.html Improve GIN index scan cost estimation (Teodor Sigaev) Jesper -- Jesper -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
