On Mon, 2011-06-13 at 13:24 -0400, Robert Haas wrote: > On Fri, Jun 3, 2011 at 3:42 AM, Rafael Martinez > > > > You can see the graph with the generation of WAL files + some extra > > information for this test here: http://folk.uio.no/rafael/total_wal/ > > > > What do you think? Shouldn't we update the documentation with some > > information about this? > > Perhaps, but we'd have to think of something intelligent to say about > it first. We can't remove the old WAL files until we successfully > checkpoint, and so I think if checkpoints are taking a very long to > complete or failing altogether, there's actually no upper bound. I > don't think we have any kind of "hard stop" where, if no log space is > available, we just refuse to process write transactions - such a thing > would seem to be rather dangerous. >
Well, a good start will be to try to identify or describe the situations where checkpoints can take very long to complete or fail altogether. I have the first one: Creating a large GIN index on a tsvector column. I don't know why, maybe somebody who knows postgres internals can explain why a creation of an index can create this situation. regards, -- Rafael Martinez Guerrero Center for Information Technology University of Oslo, Norway PGP Public Key: http://folk.uio.no/rafael/
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