Paul Tillotson <spam1011@xxxxxxxxxxxx> writes: > For the following query, postgres is running the IN subquery over and > over again (once for each row scanned in the parent table.) > I would have expected it to run the whole query once and create a hash > which would then be probed once for every row scanned in the parent > table. I assumed that it was not doing so because it thought that the > resulting hash table would exceed sort_mem, Hardly likely, considering it's estimating only 296 rows in the subquery output. My bet is that you've chosen a datatype whose comparisons are not hashable (like char(n)). What is the datatype of parentid in these tables, anyway? regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
