Re: Vacuum Blocking A Deleteion - Why?

Brad Nicholson <bnichols@ca.afilias.info> writes:
> We have been having a problem with a long running vacuum on a table 
> blocking deletes.  We have a log table on which the only activity is an 
> on going series of deletions.  The problem is experienced on a slony 
> replicated node, but I don't  think that slony is at fault here.

> My question - why is a vacuum blocking a deletion?

The problem is evidently that it's got an exclusive lock on the table:

>     17578 | 1744920 | AccessExclusiveLock      | t

which is entirely unexpected behavior for plain VACUUM in any release
later than 7.1.  I have to think that slony does have something to do
with it ... would suggest asking the slony folk about this.
        regards, tom lane