Jeff Janes <jeff.ja...@gmail.com> writes: > One thing I wanted to play with is having newly read buffers get a > usage count of 0 rather than 1. The problem is that there is no way > to test it in enough different situations to convince people it would > be a general improvement.
Hmm ... ISTM that that was discussed back when we instituted buffer usage counts, and rejected on the grounds that a newly-read buffer could then have negligible life expectancy. The clock sweep might be just about to pass over it. By starting at 1, it's guaranteed to have at least 1 sweep cycle time in which it might accumulate more hits. In other words, we have a choice of whether a buffer's initial lifetime is between 0 and 1 sweep times, or between 1 and 2 sweep times; and the discrimination against an unlucky buffer position is infinite in the first case versus at most 2X in the second case. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers