Re: Add parallelism and glibc dependent only options to reindexdb

On Mon, Jul 8, 2019 at 9:57 AM Michael Paquier <michael@paquier.xyz> wrote:
>
> On Fri, Jul 05, 2019 at 07:25:41PM +0200, Julien Rouhaud wrote:
> > On Fri, Jul 5, 2019 at 6:16 PM Peter Eisentraut <peter.eisentraut@2ndquadrant.com> wrote:
> >> Isn't that also the case for your proposal?  We are not going to release
> >> a new reindexdb before a new REINDEX.
> >
> > Sure, but my point was that once the new reindexdb is released (or if
> > you're so desperate, using a nightly build or compiling your own), it
> > can be used against any previous major version.  There is probably a
> > large fraction of users who don't perform a postgres upgrade when they
> > upgrade their OS, so that's IMHO also something to consider.
>
> I think that we need to think long-term here and be confident in the
> fact we will still see breakages with collations and glibc, using a
> solution that we think is the right API.  Peter's idea to make the
> backend-aware command of the filtering is cool.  On top of that, there
> is no need to add any conflict logic in reindexdb and we can live with
> restricting --jobs support for non-index objects.

Don't get me wrong, I do agree that implementing filtering in the
backend is a better design.  What's bothering me is that I also agree
that there will be more glibc breakage, and if that happens within a
few years, a lot of people will still be using pg12- version, and they
still won't have an efficient way to rebuild their indexes.  Now, it'd
be easy to publish an external tools that does a simple
parallel-and-glic-filtering reindex tool that will serve that purpose
for the few years it'll be needed, so everyone can be happy.

For now, I'll resubmit the parallel patch using per-table only
approach, and will submit the filtering in the backend using a new
REINDEX option in a different thread.