At Thu, 1 Oct 2020 09:05:19 +0900, Fujii Masao <masao.fu...@oss.nttdata.com> wrote in > > > On 2020/09/30 20:21, Amit Kapila wrote: > > On Tue, Sep 29, 2020 at 9:23 PM Fujii Masao > > <masao.fu...@oss.nttdata.com> wrote: > >> > >> On 2020/09/29 11:51, Masahiro Ikeda wrote: > >>> On 2020-09-29 11:43, Amit Kapila wrote: > >>>> On Tue, Sep 29, 2020 at 7:39 AM Masahiro Ikeda > >>>> <ikeda...@oss.nttdata.com> wrote: > >>> Thanks for your suggestion. > >>> I understood that the point is that WAL-related stats have just one > >>> counter now. > >>> > >>> Since we may add some WAL-related stats like pgWalUsage.(bytes, > >>> records, fpi), > >>> I think that the current approach is good. > >> > >> +1 > >> > > Okay, it makes sense to keep it in the current form if we have a plan > > to extend this view with additional stats. However, why don't we > > expose it with a function similar to pg_stat_get_archiver() instead of > > providing individual functions like pg_stat_get_wal_buffers_full() and > > pg_stat_get_wal_stat_reset_time? > > We can adopt either of those approaches for pg_stat_wal. I think that > the former is a bit more flexible because we can collect only one of > WAL information even when pg_stat_wal will contain many information > in the future, by using the function. But you thought there are some > reasons that the latter is better for pg_stat_wal?
FWIW I prefer to expose it by one SRF function rather than by subdivided functions. One of the reasons is the less oid consumption and/or reduction of definitions for intrinsic functions. Another reason is at least for me subdivided functions are not useful so much for on-the-fly examination on psql console. I'm often annoyed by realizing I can't recall the exact name of a function, say, pg_last_wal_receive_lsn or such but function names cannot be auto-completed on psql console. "select proname from pg_proc where proname like.. " is one of my friends:p On the other hand "select * from pg_stat_wal" requires no detailed memory. However subdivided functions might be useful if I wanted use just one number of wal-stats in a function, I think it is not a major usage and we can use a SQL query on the view instead. Another reason that I mildly want to object to subdivided functions is I was annoyed that a stats view makes many individual calls to functions that internally share the same statistics entry. That behavior required me to provide an entry-caching feature to my shared-memory statistics patch. regrds. -- Kyotaro Horiguchi NTT Open Source Software Center
