Jeff Boes <jboes@xxxxxxxxxxxx> writes: > What would cause an otherwise well-behaved table to start doing this? Is > this just a "dead spot" in the ANALYZE command? (By which I mean: > ANALYZE randomly sampling rows, but my data is not terribly random, so > it gets fooled?) 7.4's ANALYZE is indeed easily fooled by nonuniform tuple density. 8.0 uses a different sampling algorithm that we hope will do better. > [And here's the remaining question in my puzzled mind: ANALYZE would not > change the reltuples value, but VACUUM FULL ANALYZE did. Er-wha?] Any variant of VACUUM records the exact number of tuples that it found in its full table scan in reltuples. It's only a standalone ANALYZE that has to approximate. The case where you saw reltuples > count(*) probably came from the fact that VACUUM counts physical tuples --- that is, the difference reflects dead-but-not-yet-removable tuples. regards, tom lane
