On Tue, Mar 15, 2022 at 11:04:26AM +0900, Michael Paquier wrote: > On Mon, Mar 14, 2022 at 03:54:19PM +0530, Bharath Rupireddy wrote: >> At times, the snapshot or mapping files can be large in number and one >> some platforms it takes time for checkpoint to process all of them. >> Having the stats about them in server logs can help us better analyze >> why checkpoint took a long time and provide a better RCA. > > Do you have any numbers to share regarding that? Seeing information > about 1k WAL segments being recycled and/or removed by a checkpoint > where the operation takes dozens of seconds to complete because we can > talk about hundred of gigs worth of files moved around. If we are > talking about 100~200 files up to 10~20kB each for snapshot and > mapping files, the information has less value, worth only a portion of > one WAL segment.
I don't have specific numbers to share, but as noted elsewhere [0], I routinely see lengthy checkpoints that spend a lot of time in these cleanup tasks. [0] https://postgr.es/m/18ED8B1F-7F5B-4ABF-848D-45916C938BC7%40amazon.com -- Nathan Bossart Amazon Web Services: https://aws.amazon.com
