Mark Kirkwood <[EMAIL PROTECTED]> writes:
> Jim C. Nasby wrote:
>> Good point. :/ I'm guessing there's no easy way to see how many blocks
>> for a given relation are in shared memory, either...
> contrib/pg_buffercache will tell you this -
I think the key word in Jim's comment was "easy", ie, cheap. Grovelling
through many thousands of buffers to count the matches to a given
relation doesn't sound appetizing, especially not if it gets done over
again several times during each query-planning cycle. Trying to keep
centralized counts somewhere would be even worse (because of locking/
contention issues).
regards, tom lane
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
