On Mon, Nov 30, 2020 at 4:53 PM Alvaro Herrera <alvhe...@alvh.no-ip.org> wrote: > > On 2020-Sep-30, Michael Paquier wrote: > > > + <para> > > + <command>CREATE INDEX</command> (including the > > <literal>CONCURRENTLY</literal> > > + option) commands are included when <command>VACUUM</command> calculates > > what > > + dead tuples are safe to remove even on tables other than the one being > > indexed. > > + </para> > > FWIW, this is true as well for REINDEX CONCURRENTLY because both use > > the same code paths for index builds and validation, with basically > > the same waiting phases. But is CREATE INDEX the correct place for > > that? Wouldn't it be better to tell about such things on the VACUUM > > doc? > > Yeah, I think it might be more sensible to document this in > maintenance.sgml, as part of the paragraph that discusses removing > tuples "to save space". But making it inline with the rest of the flow, > it seems to distract from higher-level considerations, so I suggest to > make it a footnote instead.
I have mixed feelings about wholesale moving it; users aren't likely to read the vacuum doc when considering how running CIC might impact their system, though I do understand why it otherwise fits there. Even if the primary details are in the vacuum, I tend to think a reference note (or link to the vacuum docs) in the create index docs would be useful. The principle here is that 1.) vacuum is automatic/part of the background of the system, not just something people trigger manually, and 2.) we ought to document things where the user action triggering the behavior is documented. > I'm not sure on the wording to use; what about this? The wording seems fine to me. This is a replacement for what was 0002 earlier? And 0001 from earlier still seems to be a useful standalone patch? James
