Details
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Bug
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Status: Closed
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Minor
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Resolution: Fixed
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None
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None
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New
Description
Because we "cascade" merges for an optimize... if you also delete documents while the merges are running, then the merge policy will see the resulting single segment as still not optimized (since it has pending deletes) and do a single-segment merge, and will repeat indefinitely (as long as your app keeps deleting docs).
One simple way to fix this would be to have IW disregard the MergePolicy if ever it asks to do a single-segment merge of a segment that had already been produced by merging for the current optimize call.
But... I don't really like this, as it could be some unusual MergePolicy out there sometimes wants to do such merging.
So I think a better solution, but API breaking to the MergePolicy, which is OK because it's @experimental, is to change the segmentsToOptimize argument; currently it's just a set recording which segments need to be optimized away. I think we should change it to a Map<String,Boolean>, where the Boolean indicates whether this segment had been created by a merge in the current optimize session. Then I'll fix our MPs to not cascade in such a case.