On Thu, 29 Mar 2007, Magnus Hagander wrote:

I've included a couple of more counters per ideas from Greg Smith in his
logging patch.


I just submitted a patch that logs the remaining things of value from my original that couldn't be derived from the information you're collecting. Between them I'm happy that a lot of previously hidden performance issues can now be monitored--not necessarily easily, but it's at least possible.

I made one small change to your code in there as well I wanted to highlight here. You updated the buffers written by checkpoints one at a time as they wrote out. When I tried to develop something that monitored pg_stat_bgwriter looking for when checkpoints happened, this made it difficult to answer the important question "how many buffers did the last checkpoint write?" just from the stats structure because I assumed it's possible to get a view in the middle of the checkpoint. It took watching both the total and the checkpoint count, and that was hard to work with.

I modified things so that the checkpoint buffers written number gets updated in one shot when the buffer flush is done. No partial results, much easier to monitor: when the buffers_checkpoint value changes, the difference from the previous value is what the last checkpoint wrote. I needed that total anyway which is why I just slipped it into the other patch.

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

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