Amit Kapila wrote: > On Tue, Jul 11, 2017 at 6:51 AM, AP <a...@zip.com.au> wrote: > > On Fri, Jul 07, 2017 at 05:58:25PM +0530, Amit Kapila wrote:
> >> I can understand your concerns. To address first concern we need to > >> work on one or more of following work items: (a) work on vacuums that > >> can be triggered on insert only workload (it should perform index > >> vacuum as well) (b) separate utility statement/function to squeeze > >> hash index (c) db internally does squeezing like after each split, so > >> that chances of such a problem can be reduced, but that will be at the > >> cost of performance reduction in other workloads, so not sure if it is > >> advisable. Among these (b) is simplest to do but may not be > >> convenient for the user. > > > > (a) seems like a good compromise on (c) if it can be done without disruption > > and in time. > > (b) seems analogous to the path autovcauum took. Unless I misremember, > > before > > autovacuum we had a cronjob to do similar work. It's probably a sane > > path > > to take as a first step on the way to (a) > > (c) may not be worth the effort if it compromises general use, though > > perhaps > > it could be used to indicate to (a) that now is a good time to handle > > this bit? > > Nice summarization! I think before doing anything of that sort we > need opinions from others as well. If some other community members > also see value in doing one or multiple of above things, then I can > write a patch. I haven't read the thread, but in late PG10 autovacuum gained the idea of "work items" that can be plugged from other parts of the server; currently BRIN uses it to cause a range to be summarized right after the next one starts being filled. This is activated separately for each index via a reloption. Perhaps something like that can be used for hash indexes? See commit 7526e10224f0792201e99631567bbe44492bbde4. -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
