"Phoenix Kiula" <phoenix.kiula@xxxxxxxxx> writes: > A couple of questions about the "most_common_vals" stuff in pg_stats > for a high traffic table: > 1. Can I tell the stats collector to collect only values of a column > where a certain regex is matched? Not directly, but you could set up a partial index defined that way, and ANALYZE would collect stats on the index contents. Whether the planner could actually do anything with the information is another story; I suspect you're wasting your time with this idea. > 2. Secondly, for a unique column in the table, will the > "most_common_vals" always be -1? I guess this could make sense, but I > was wondering if the stats collector could somehow collect at least > 1000 unique values to improve at least some performance. most_common_vals will (and should) be empty if there aren't actually any common values, but aren't you getting a histogram? Exactly what performance do you think will be improved? regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
