Greg Smith <[EMAIL PROTECTED]> writes: > Based on my observations of buffer cache statistics, the number of pinned > buffers at any time is small enough that in a reasonably sized buffer > cache, I wouldn't expect a change in the pinned usage_count behavior to > have any serious impact.
Fair enough. The patch I put up earlier tonight bumps usage_count at PinBuffer instead of UnpinBuffer time, and leaves the clock sweep behavior unchanged, which means that a buffer that had stayed pinned for more than a clock-sweep cycle time could get recycled almost instantly after being unpinned. That seems intuitively bad. If we make the clock sweep code not decrement usage_count of a pinned buffer then the problem goes away. I had expressed some discomfort with that idea, but I've got to admit that it's only a vague worry not anything concrete. Barring objections I'll adjust the patch to include the clock-sweep change. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend