Kevin Kempter <kevink at consistentstate.com> writes:
> we created a new replication set 4 hrs ago and we continue to see messages 
> like this in the logs from the slave (the slon logs):
>
> 2010-02-02 21:04:23 PST DEBUG1 remoteWorkerThread_1: connected to provider DB
> 2010-02-02 21:04:23 PST WARN   remoteWorkerThread_1: transactions earlier than 
> XID 31685677 are still in progress
> 2010-02-02 21:04:23 PST WARN   remoteWorkerThread_1: data copy for set 2 
> failed 178 times - sleep 60 seconds
>
>
> The master is busy but I see no processes in pg_stat_activity that are waiting 
> and no rows in pg_locks have granted = 'f' (all rows are granted = 't')
>
> also our st_lag_num_events in sl_status have climbed to 2729 since we ran the 
> create set command
>
>
>  any thoughts?

Well, you'll need to figure out what is the transaction that is holding
onto that old XID, and see if you can terminate it.

http://www.slony.info/documentation/faq.html#AEN7300

You can look at pg_locks to see what's holding on to old transactions.

There are numerous reasons why this might happen, not all of which
permit the same solutions...

 - If your accounting guys are running some important report, perhaps
   you have to wait.

 - If you have an application that uses a framework that leaves
   idle-in-transaction connections lying around, then it may be
   fair to kill off some transactions

 - If a backup is under way, then killing that connection mightn't be
   the best idea!
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Christopher Browne
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