On Sun, 1 Apr 2007, Russell Smith wrote:

Currently the max buffer count is 5. But is that a complete safe assumption? Maybe a compile time check that BM_MAX_USAGE_COUNT is < 16k would ensure that things don't go wrong?


I actually wasn't even aware that was a hard limit; I just assumed that all my systems just never got over 5 before the LRU hit them. How 'bout that.

I'm all for paranoia, but the idea of letting LRU usage counts go over 16 bits seems pretty unlikely with the current approach. That would mean those pages would need 64K passes over the buffer cache before they could get evicted, which would take quite a while. My bet is that bufferid gets expanded from 32 bits before that happens, which would break pg_buffercache similarly and isn't being checked for either.

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* Greg Smith [EMAIL PROTECTED] http://www.gregsmith.com Baltimore, MD

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