Sam Nelson wrote:
One of our clients has an lru_max_dirty setting of 1000 and a bgwriter_delay of 200, but we're still seeing much higher growth in the buffers_checkpoint than buffers_clean, with buffers_checkpoint increasing at about 20 times the rate that buffers_clean is. We don't see very much growth in the maxwritten_clean, though - something like one every couple of days.
The background writer can only clean data pages that haven't been used in a while. In your case, it sounds like most of the things that are getting dirty are being touched enough that they never meet its criteria. There's nothing wrong with that. Writing out dirty buffers only once per checkpoint is in theory the most efficient way to handle regularly changed data.
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