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https://issues.apache.org/jira/browse/COUCHDB-1080?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13002055#comment-13002055
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Randall Leeds commented on COUCHDB-1080:
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With your patch, commit_to_both can return errors. Before it just threw
badmatch exceptions. The old way, the only path to the case clause with my log
message was when a successful _ensure_full_commit happened but the
instance_start_time did not match (source or target crashed or closed, may have
lost some changes we replicated, so we can't checkpoint).
I like the way you changed it, but I also like the helpful error message I
added. Maybe now we can have four case clauses in do_checkpoint and that way we
can be very clear to the user about what went wrong? Does this make sense to
you now?
> fail fast with checkpoint conflicts
> -----------------------------------
>
> Key: COUCHDB-1080
> URL: https://issues.apache.org/jira/browse/COUCHDB-1080
> Project: CouchDB
> Issue Type: Improvement
> Components: Replication
> Affects Versions: 1.0.2
> Reporter: Randall Leeds
> Fix For: 1.1, 1.2
>
> Attachments: COUCHDB-1080-fdmanana.patch,
> paranoid_checkpoint_failure.patch, paranoid_checkpoint_failure_v2.patch
>
>
> I've thought about this long and hard and probably should have submitted the
> bug a long time ago. I've also run this in production for months.
> When a checkpoint conflict occurs it is almost always the right thing to do
> to abort.
> If there is a rev mismatch it could mean there's are two conflicting
> (continuous and one-shot) replications between the same hosts running.
> Without reloading the history documents checkpoints will continue to fail
> forever. This could leave us in a state with many replicated changes but no
> checkpoints.
> Similarly, a successful checkpoint but a lost/timed-out response could cause
> this situation.
> Since the supervisor will restart the replication anyway, I think it's safer
> to abort and retry.
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