Re: "debug_invalidate_system_caches_always" is too long

On Sun, Jul 04, 2021 at 04:27:13PM -0400, Tom Lane wrote:
> As I've been poking around in this area, I find myself growing
> increasingly annoyed at the new GUC name
> "debug_invalidate_system_caches_always". It is too d*mn long.
> It's a serious pain to type in any context where you don't have
> autocomplete to help you. I've kept referring to this type of
> testing as CLOBBER_CACHE_ALWAYS testing, even though that name is
> now obsolete, just because it's so much shorter. I think we need
> to reconsider this name while we still can.
>
> I do agree with the "debug_" prefix given that it's now visible to
> users. However, it doesn't seem that hard to save some space in
> the rest of the name. The word "system" is adding nothing of value,
> and the word "always" seems rather confusing --- if it does
> something "always", why is there more than one level? So a simple
> proposal is to rename it to "debug_invalidate_caches".

I agree with all that. The word "always" has been misinformation, given the
multiple levels available.

> However, I think we should also give serious consideration to
> "debug_clobber_cache" or "debug_clobber_cache_always" for continuity
> with past practice (though it still feels like "always" is a good
> word to lose now). "debug_clobber_caches" is another reasonable
> variant.

https://en.wikipedia.org/wiki/Clobbering refers to cases where storage had no
changes to its accessibility but now contains different data. That doesn't
match InvalidateSystemCaches() especially well, so I think dropping that word
has been a good step. Some other shorter terms could be debug_flush_caches,
debug_rebuild_caches, or debug_expire_caches. (debug_caches is tempting, but
that may ensnare folks looking for extra logging rather than a big slowdown.)