Re: reindex concurrently and two toast indexes

On Tue, Mar 03, 2020 at 05:06:42PM +0900, Michael Paquier wrote:
> Attached is a draft patch to take care of that problem for HEAD.  It
> still needs a lot of polishing (variable names are not actually old
> or new anymore, etc.) but that's enough to show the idea.  If a version
> reaches PG12, we would need to keep around the past routines to avoid
> an ABI breakage, even if I doubt there are callers of it, but who
> knows..

Or actually, a more simple solution is to abuse of the two existing
routines so as the dependency switch is done the other way around,
from the new index to the old one.  That would visibly work because
there is no CCI between each scan, and that's faster because the scan
of pg_depend is done only on the entries in need of an update.  I'll
look at that again tomorrow, it is late here and I may be missing
something obvious.
--
Michael