On Wed, Sep 16, 2020 at 2:30 PM Michael Paquier <michael@paquier.xyz> wrote:
> On Tue, Sep 15, 2020 at 10:01:18AM -0400, Tom Lane wrote:
> > Seems like a good argument, but you'd have to be careful about the
> > final state when you stop overriding update_process_title --- it can't
> > be left looking like it's still-in-progress on some random WAL file.
> > (Compare my nearby gripes about walsenders being sloppy about their
> > pg_stat_activity and process title presentations.)
>
> Another thing to be careful here is WIN32, see 0921554. And slowing
> down recovery is never a good idea.
Right, that commit makes a lot of sense because it suppresses many
system calls that happen for each query. The same problem existed on
older FreeBSD versions and I saw that costing ~10% of TPS on read-only
pgbench. In other commits I've been removing system calls that happen
for every WAL record. But in this thread I'm talking about an update
per 16MB WAL file, which seems like an acceptable ratio to me.