Hi, Thanks for running this!
On 2017-08-15 03:27:00 +0200, Tomas Vondra wrote: > Granted - this chart does not show latency, so it's not a complete > picture. That'd be quite useful to see here, too. > Also, if you care about raw OLTP performance you're probably already running > on flash, where this does not seem to be an issue. It's also not an issue if > you have RAID controller with write cache, which can absorb those writes. > And of course, those machines have reasonable dirty_background_bytes values > (like 64MB or less). The problem is that dirty_background_bytes = 64MB is *not* actually a generally reasonable config, because it makes temp table, disk sort, etc operations flush way too aggressively. > b) The "flushing enabled" case seems to be much more sensitive to WAL > segment size increases. It seems the throughput drops a bit (by 10-20%), for > some segment sizes, and then recovers. The behavior seems to be smooth (not > just a sudden drop for one segment size) but the value varies depending on > the scale, test type (tpc-b /simple-update). That's interesting. I presume you've not tested with separate data / xlog disks? Greetings, Andres Freund -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers