Julian Reschke created OAK-8002:
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Summary: RDBDocumentStore: MissingLastRevSeeker slow on DB2
Key: OAK-8002
URL: https://issues.apache.org/jira/browse/OAK-8002
Project: Jackrabbit Oak
Issue Type: Technical task
Components: rdbmk
Reporter: Julian Reschke
Assignee: Julian Reschke
This is because the generic {{MissingLastRevSeeker}} gets candidate in batches
(of 100), but in order to do batching, requires results to be sorted by ID.
For DB2 we by default have indices on both ID and MODIFIED, but contrary to our
expection a query that involves both indices does not perforn well. Adding a
compound index on ID *and* MODIFIED improves performance, but I'm hesitant to
add this just to improve a recovery job.
A more logical approach would be not to require batching/sorting by adopting
the approach in {{MongoMissingLastRevSeeker}} which doesn't require sorting by
ID in the first place.
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