Kurt Overberg <kurt@xxxxxxxxxxxxxxxxx> writes: > ... Turning off bitmap scans definitely seems > to help things, I really seriously doubt that. On queries like this, where each inner scan is fetching a couple hundred rows, the small extra overhead of a bitmap scan should easily pay for itself. I think you're looking entirely at caching effects that allow a re-read of the same data to go faster. You might try running the same query plan several times in a row and noting the lowest time, then repeat for the other query plan. This will get you comparable fully-cached times, which I bet will be very close to the same. regards, tom lane
