Hi, чт, 28 мар. 2019 г. в 00:32, Alvaro Herrera <alvhe...@2ndquadrant.com>:
> On 2019-Mar-27, Darafei "Komяpa" Praliaskouski wrote: > > > Attached is sketch of small patch that fixes several edge cases with > > autovacuum. Long story short autovacuum never comes to append only > tables, > > killing large productions. > > Yeah, autovac is not coping with these scenarios (and probably others). > However, rather than taking your patch's idea verbatim, I think we > should have autovacuum use separate actions for those two (wildly > different) scenarios. For example: > > * certain tables would have some sort of partial scan that sets the > visibility map. There's no reason to invoke the whole vacuuming > machinery. I don't think this is limited to append-only tables, but > rather those are just the ones that are affected the most. > What other machinery runs on VACUUM invocation that is not wanted there? Since Postgres 11 index cleanup is already skipped on append-only tables. > * tables nearing wraparound danger should use the (yet to be committed) > option to skip index cleaning, which makes the cleanup action faster. > Again, no need for complete vacuuming. > "Nearing wraparound" is too late already. In Amazon, reading table from gp2 after you exhausted your IOPS burst budget is like reading a floppy drive, you have to freeze a lot earlier than you hit several terabytes of unfrozen data, or you're dead like Mandrill's Search and Url tables from the link I shared. > > > -- > Álvaro Herrera https://www.2ndQuadrant.com/ > PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services > -- Darafei Praliaskouski Support me: http://patreon.com/komzpa
