Tom Lane wrote: > Bruce Momjian <pgman@candle.pha.pa.us> writes: > > One idea would be to look at the table file size first. If it has zero > > blocks, lock the table and if it still has zero blocks, do the no-WAL > > copy. > > I think that's a bad idea. It would make the behavior unpredictable > --- sometimes a COPY will take an exclusive lock, and other times not; > and the reason why is at a lower semantic level than the user is > supposed to know about. > > Before you say "this is not important", consider the nontrivial risk > that the stronger lock will cause a deadlock failure. I don't think > that it's acceptable for lock strength to be unpredictable.
Yea, but you are only doing the lock if the table is zero pages. Doesn't that help? Maybe not. I do like the LOCK keyword if we have to use one to enable this functionality, but I am suspecting people will want this functionality in pg_dump output. How do we do that? Just make it the default for pg_dump output? -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend