Re: Should pg_current_wal_location() become pg_current_wal_lsn()

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Fri, Apr 14, 2017 at 4:28 AM, Kyotaro HORIGUCHI
> <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
>> Similariliy, these columns may need renaming.

> Personally, I would be inclined not to tinker with this, not just
> because we're after freeze but because it doesn't seem like an
> improvement to me. Referring to an LSN as location seems fine to me;
> I mean, granted, it's one specific kind of location, but that doesn't
> make it wrong.

In a green field it would be perfectly fine --- but I think Kyotaro-san's
point is about consistency. If all the other exposed names that involve
the same concept use "lsn", then it's fair to say that it's a bad idea
for these four column names to be randomly different from the rest.

Now this is a pre-existing problem: those column names existed in 9.6,
and so did some of the ones named using "lsn". But we've added more
of the latter in v10. I think the real problem right now is that nobody
has a rule to follow about which way to name new exposed references to
the concept, and that's simply bad.

It's possible that we should say that backwards compatibility outweighs
consistency and therefore it's too late to change these names. But
I think your argument above is missing the point.

regards, tom lane