Re: Patch to remove/report orphaned files

Bruce Momjian <pgman@candle.pha.pa.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