"Jim C. Nasby" <jnasby 'at' pervasive.com> writes: > If you feel like running some tests, you need to change > > run_cost += max_IO_cost + csquared * (min_IO_cost - max_IO_cost); > > in src/backend/optimizer/path/costsize.c to something like > > run_cost += max_IO_cost + abs(indexCorrelation) * (min_IO_cost - > max_IO_cost);
Short after the beginning of a discussion about planner associating too high cost for index scan, I'm suggested to change source-code.. I'm already frightened about the near future :) > That might not produce a perfect cost estimate, but I'll wager that it > will be substantially better than what's in there now. FYI, see also > http://archives.postgresql.org/pgsql-performance/2005-04/msg00669.php Sad that Tom didn't share his thoughts about your cost algorithm question in this message. -- Guillaume Cottenceau ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
