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From "Chetan Mehrotra (JIRA)" <j...@apache.org>
Subject [jira] [Created] (OAK-3071) Add a compound index for _modified + _id
Date Thu, 02 Jul 2015 18:09:04 GMT
Chetan Mehrotra created OAK-3071:

             Summary: Add a compound index for _modified + _id
                 Key: OAK-3071
                 URL: https://issues.apache.org/jira/browse/OAK-3071
             Project: Jackrabbit Oak
          Issue Type: Improvement
          Components: mongomk
            Reporter: Chetan Mehrotra
             Fix For: 1.2.3, 1.3.4, 1.0.17

As explained in OAK-1966 diff logic makes a call like

bq. db.nodes.find({ _id: { $gt: "3:/content/foo/01/", $lt: "3:/content/foo010" }, _modified:
{ $gte: 1405085300 } }).sort({_id:1})

For better and deterministic query performance we would need to create a compound index like
\{_modified:1, _id:1\}. This index would ensure that Mongo does not have to perform object
scan while evaluating such a query.

Care must be taken that index is only created by default for fresh setup. For existing setup
we should expose a JMX operation which can be invoked by system admin to create the required
index as per maintenance window

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