Thom Brown <thom@xxxxxxxxx> writes: > I've created a test table containing 21 million random dates and > times, but I get wildly different results when I introduce a > functional index then ANALYSE again, even though it doesn't use the > index: As Peter said, the existence of the index causes ANALYZE to gather stats about the expression, which will affect rowcount estimates whether or not the planner chooses to use the index. > And as a side note, how come it's impossible to get the planner to use > an index-only scan to satisfy the query (disabling sequential and > regular index scans)? Implementation restriction - we don't yet have a way to match index-only scans to expressions. regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
