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Paul Hirst commented on COUCHDB-1230: ------------------------------------- It's quite likely I could borrow some hardware in the next couple of weeks to try this out. I'll see what I can do. I don't have anywhere immediately to test this. Thanks. > Replication slows down over time > -------------------------------- > > Key: COUCHDB-1230 > URL: https://issues.apache.org/jira/browse/COUCHDB-1230 > Project: CouchDB > Issue Type: Bug > Components: Replication > Affects Versions: 1.0.2, 1.1 > Environment: Ubuntu 10.04, > Reporter: Paul Hirst > Attachments: sequence_number.png > > > I have two databases which were replicated in the past, one is running 1.0.2. > I shall call this the source database. The other is running 1.1.0, I shall > call this the target database. > The source and target are bidirectionally replicated using a push and pull > replication from the target (using a couple of documents in the new > _replicator database). > The source database is in production and is getting changes applied to it > from live systems. The target is only participating in replication and isn't > being used directly by any production systems. > The database has about 50 million documents many of these will have been > updated a handful of times. The database is about 500G after compaction, but > the source database is currently at about 900G as it hasn't been compacted > for a while. > The databases were replicated in the past however this replication was torn > down when the target was upgraded from 1.0.2 to 1.1.0. When replication was > reenabled the system wasn't able to pick up were it left off and had to > reenumerate all the documents again. This process initially started quickly > but after a while ground to a halt such that the target actually stopped > making progress against the source database. > I found that restarting replication starts the process running again at a > decent speed for a while. I did this by deleting and recreating the > appropriate document in the _replicator database on the target. > I have graphed the last_seq of the target database against time for about a > day, noting when replication was manually restarted. I shall try to attach > the graph if possible. It shows a clear improvement in replication speed > after restarting replication. > I previously witnessed this behaviour between 1.0.2 databases but didn't grab > any stats at the time but I don't think it's a new problem. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira