4 ms·
Just in case you weren't already aware, the count(*) issue should be significantly improved for some queries in postgres 9.2, thanks to the addition of covering
by AlisdairO 14y ago
Just in case you weren't already aware, the count(*) issue should be significantly improved for some queries in postgres 9.2, thanks to the addition of covering indexes.
- einhverfr 14y agoThere was discussion on pgsql-general a bit before the release. It appears that physically sequential scan of a table is about as fast as key-order sequential scan of a covering index. To speed up a lot, I think you'd need to be able to scan an index in physical order which is not currently supported. Now if you are using SSD's yeah, you could tweak the planner settings enough to cause it to make an index scan perhaps, and maybe you'd see a modest performance increase, but even there it appears the operating system's prefetch logic really does come to the rescue of a sequential scan of a table in physical order.
- AlisdairO 14y agoah, that's unfortunate :-(