On 6/5/15 6:54 PM, deavid wrote:
So the problem is: i see a low iowait, and CPU time for one core is at 80-90% most of the time. I can buy more ram, better disks, or cpu's with more cores. But one cpu core would have more-or-less the same speed no matter how much money you invest. When someone wants a delayed-write index is similar to setting "synchronous_commit = off". We want to give an OK to the backend as soon as is possible and do this work in background. But we also want some reliability against crashes. Also, if the task is done in background it may be done from other backend, so probably several indexes could be packed at once using different backend processes. We could use the entire cpu if our index writes aren't tied to the session who wrote the row.
Something that might help here would be doing the index maintenance in parallel via background workers. There's now enough parallelism infrastructure that it shouldn't be too hard to hack up a quick test of that.
-- Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX Data in Trouble? Get it in Treble! http://BlueTreble.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
