Re: SSI patch version 14

On Tue, Feb 08, 2011 at 10:14:44AM -0600, Kevin Grittner wrote:
> I do have some concern that if this defaults to too low a number,
> those who try SSI without bumping it and restarting the postmaster
> will not like the performance under load very much.  SSI performance
> would not be affected by a low setting under light load when there
> isn't a long-running READ WRITE transaction.

If we're worried about this, we could add a log message the first time
SummarizeOldestCommittedXact is called, to suggest increasing the GUC
for number of SerializableXacts. This also has the potential benefit of
alerting the user that there's a long-running transaction, in case that's
unexpected (say, if it were caused by a wedged client)

I don't have any particular opinion on what the default value of the
GUC should be.

Dan

-- 
Dan R. K. Ports              MIT CSAIL                http://drkp.net/