On Mon, 29 Jun 2020 at 20:37, Amit Kapila <amit.kapil...@gmail.com> wrote: > > On Mon, Jun 29, 2020 at 10:26 AM Masahiko Sawada > <masahiko.saw...@2ndquadrant.com> wrote: > > > > On Fri, 26 Jun 2020 at 17:53, Amit Kapila <amit.kapil...@gmail.com> wrote: > > > > > > On Fri, Jun 26, 2020 at 11:31 AM Masahiko Sawada > > > <masahiko.saw...@2ndquadrant.com> wrote: > > > > > > > > On Thu, 25 Jun 2020 at 19:35, Amit Kapila <amit.kapil...@gmail.com> > > > > wrote: > > > > > > > > > > > > > > > Today, I thought about it again, and if we consider the point that > > > > > logical_decoding_work_mem value doesn’t change much then having the > > > > > stats at slot-level would also allow computing > > > > > logical_decoding_work_mem based on stats. Do you think it is a > > > > > reasonable assumption that users won't change > > > > > logical_decoding_work_mem for different processes (WALSender, etc.)? > > > > > > > > FWIW, if we use logical_decoding_work_mem as a threshold of starting > > > > of sending changes to a subscriber, I think there might be use cases > > > > where the user wants to set different logical_decoding_work_mem values > > > > to different wal senders. For example, setting a lower value to > > > > minimize the latency of synchronous logical replication to a near-site > > > > whereas setting a large value to minimize the amount of data sent to a > > > > far site. > > > > > > > > > > How does setting a large value can minimize the amount of data sent? > > > One possibility is if there are a lot of transaction aborts and > > > transactions are not large enough that they cross > > > logical_decoding_work_mem threshold but such cases shouldn't be many. > > > > Yeah, this is what I meant. > > > > I agree that it would not be a common case that the user sets > > different values for different processes. Based on that assumption, I > > also think having the stats at slot-level is a good idea. > > > > Okay. > > > But I might > > want to have the reset function. > > > > I don't mind but lets fist see how the patch for the basic feature > looks and what is required to implement it? Are you interested in > writing the patch for this work?
Yes, I'll write the draft patch. Regards, -- Masahiko Sawada http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
