Re: pgsql: Rename "pg_clog" directory to "pg_xact".

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Fri, Mar 17, 2017 at 10:04 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> There should probably have been a catversion bump in here.

> I thought about it, but:

> * The catalog version number is used to flag incompatible changes in
> * the PostgreSQL system catalogs. Whenever anyone changes the format of
> * a system catalog relation, or adds, deletes, or modifies standard
> * catalog entries in such a way that an updated backend wouldn't work
> * with an old database (or vice versa), the catalog version number
> * should be changed.

I think the key part of that is "an updated backend wouldn't work
with an old database (or vice versa)", which is certainly true of
this commit. In general, there ought to be a version bump somewhere
anytime that a developer would have to re-initdb or pg_upgrade.
In some cases you can bump the WAL page version or something else
that's more specific to the change, but catversion is the fallback
solution otherwise.

> I see your point, of course, I'm just explaining why I didn't do it.

Understood, but I think you're wrong.

regards, tom lane