Re: Hypothetical indexes using BRIN broken since pg10

On 2019-Sep-24, Julien Rouhaud wrote:

> On Mon, Sep 9, 2019 at 5:03 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:

> > Whether we should bother back-patching a less capable stopgap fix
> > is unclear to me.  Yeah, it's a bug that an index adviser can't
> > try a hypothetical BRIN index; but given that nobody noticed till
> > now, it doesn't seem like there's much field demand for it.
> > And I'm not sure that extension authors would want to deal with
> > testing minor-release versions to see if the fix is in, so
> > even if there were a back-patch, it might go unused.
> 
> FWIW I maintain such an extension and testing for minor release
> version is definitely not a problem.

I think the danger is what happens if a version of your plugin that was
compiled with the older definition runs in a Postgres which has been
recompiled with the new code.  This has happened to me with previous
unnoticed ABI breaks, and it has resulted in crashes in production
systems.  It's not a nice situation to be in.

If the break is benign, i.e. "nothing happens", then it's possibly a
worthwhile change to consider.  I suppose the only way to know is to
write patches for both sides and try it out.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services