Re: Renaming of pg_xlog and pg_clog

On Thu, Oct 20, 2016 at 2:23 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> On Thu, Oct 20, 2016 at 2:09 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> We have the two precedents "pg_subtrans" and "pg_multixact", so
>>> unless we want to get into renaming those too, I think "pg_trans"
>>> and "pg_xact" are really the only options worth considering.
>>>
>>> Personally I'd go for "pg_trans", but it's only a weak preference.
>
>> Heaven forfend we actually use enough characters to make it self-documenting.
>
> $ ls $PGDATA
> PG_VERSION pg_dynshmem/ pg_notify/ pg_stat_tmp/ postgresql.auto.conf
> base/ pg_hba.conf pg_replslot/ pg_subtrans/ postgresql.conf
> global/ pg_ident.conf pg_serial/ pg_tblspc/ postmaster.opts
> pg_clog/ pg_logical/ pg_snapshots/ pg_twophase/ postmaster.pid
> pg_commit_ts/ pg_multixact/ pg_stat/ pg_wal/
>
> I don't see one single one of those subdirectory names that I'd call
> self-documenting. Are you proposing we rename them all with carpal-
> tunnel-syndrome-promoting names?

No. Are you proposing that self-documenting names are a bad thing
rather than a good thing?

> There's certainly some case to be made for renaming at least one of
> "pg_subtrans" and "pg_multixact" so that these three similarly-purposed
> subdirectories can all have similar names. But I think on the whole
> that's (a) fixing what ain't broken, and (b) making it even more unlikely
> that we'll ever get to consensus on changing anything. We've managed to
> agree that we need to change the names ending in "log"; let's do that
> and be happy that we've removed one foot-gun from the system.

I agree that there is an overwhelming consensus in favor of getting
"log" out of the names, but I do not agree that the only two possible
alternative names are "pg_trans" and "pg_xact", which strikes me as
being akin to saying that the only two options for dinner tonight are
overripe peaches and lunch meats a week past the sell-by date. If I
had to pick only between those two, I suppose I'd go with "pg_xact"
which is clear enough to someone familiar with PostgreSQL internals,
as opposed to "pg_trans" which I don't think will be clear even to
those people. But I don't like either one very much.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company