Dan Libby <dan@xxxxxxxxx> writes: > Or failing that, I'd at least like to understand why the planner > is deciding not to use the category_lang index when the result > set is coming from a function instead of a "regular" table. The planner defaults to assuming that set-returning functions return 1000 rows (as you can see in the EXPLAIN output). A plan that would win for a single returned row would lose badly at 1000 rows ... and vice versa. See the archives for various debates about how to get a better estimate; it's not an easy problem. regards, tom lane
