Re: Patch to remove/report orphaned files

Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> The only issue with oid wraparound is that it will not report orphaned
> files from the last vacuum to the wraparound time, which seems OK.

s/seems OK/means that it's completely useless once wrap has occurred/.
Moreover, it will start complaining about freshly-created files whose
pg_class rows aren't committed yet. Checking OID in this way is simply
wrong, and we should not install such a kluge without an overwhelming
reason to do it. I see no overwhelming need for this thing. In fact,
I'm not convinced that there's any need for it.

> We don't know problems we have with orphaned files because we don't
> detect them now. We know we have left over sort files because people
> complain about them, so odds are we have these others out there too.

Two points about that. One, this won't detect them with any
reliability; what it will do is generate false, impossible-to-reproduce
problem reports --- maybe even induce DBAs to manually delete files that
they needed. ("The message says file 543242 is orphan, so I can get
rid of it without checking further.") Two, we don't know that we still
have such a problem in current sources. The orphaned-sort-file reports
that I remember are all from pre 7.0, when we didn't have a mechanism
that would clean them out after elog(ERROR). I don't think there is
evidence to justify that we still need such a detector. We certainly
don't need it bad enough to justify installing a not-quite-correct kluge.

regards, tom lane