"Carlos Moreno" <moreno_pg@xxxxxxxxxxx> writes: > I'm now thinking that the problem with my logic is that the system does > not keep anything in memory (or not all tuples, in any case), since it > is only counting, so it does not *have to* keep them That's really not how it works. When Postgres talks to the OS they're just bits. There's no cache of rows or values or anything higher level than bits. Neither the OS's filesystem cache nor the Postgres shared memory knows the difference between live or dead rows or even pages that don't contain any rows. > and since the total amount of reading from the disk exceeds the amount of > physical memory, then the valid tuples are "pushed out" of memory. That's right. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
