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From "Adam Kocoloski (JIRA)" <j...@apache.org>
Subject [jira] Commented: (COUCHDB-686) Improve ordering of replication
Date Wed, 10 Mar 2010 15:49:27 GMT

    [ https://issues.apache.org/jira/browse/COUCHDB-686?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12843602#action_12843602
] 

Adam Kocoloski commented on COUCHDB-686:
----------------------------------------

Replication always uses the changes feed if it's available.  The rationale for not using include_docs=true
is that for some replications the target already has a large fraction of the updates.  In
those cases it can be wasteful to transfer the full document.

However, that's probably the exception to the rule.  A nice optimization might be for the
replicator to track the fraction of source updates which are present on the target, and if
that fraction drops too low, just start including docs directly in the changes feed.  Or at
least, to stop checking _missing_revs on the target.  But that's tangential to this discussion.

> Improve ordering of replication
> -------------------------------
>
>                 Key: COUCHDB-686
>                 URL: https://issues.apache.org/jira/browse/COUCHDB-686
>             Project: CouchDB
>          Issue Type: Improvement
>          Components: Replication
>    Affects Versions: 0.10.1
>            Reporter: Dirkjan Ochtman
>            Priority: Minor
>             Fix For: 0.12
>
>
> Currently, (continuous) replication almost preserves the ordering of the updates. It
would be nice if this could be fixed so that the order of outgoing updates fully corresponds
to the order inside the source database. While this may fall down in some clustering situations,
it's a great guarantee to provide in many smaller situations involving an ordered stream of
documents/updates.

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