Alex Parvulescu created OAK-4812:
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             Summary: Reduce calls to SegmentStore#newSegmentId from the 
Segment class
                 Key: OAK-4812
                 URL: https://issues.apache.org/jira/browse/OAK-4812
             Project: Jackrabbit Oak
          Issue Type: Improvement
          Components: segment-tar
            Reporter: Alex Parvulescu
            Priority: Minor


OAK-4631 introduced a change in records handling in a segment that will amplify 
the number of calls to {{SegmentStore#newSegmentId}} by the number of external 
references [0]. It usually is the case that there are a lot of record 
references that point to the same segment id, and the existing 
{{recordIdCache}} would not help much in this case.
The scenario I'm seeing for offline compaction (might be a bit biased) is a 
full traversal of segments that increases pressure on the {{SegmentIdTable}} by 
calling {{newSegmentId}} with a lot of already existing segments.
I'm creating this issue as an 'Improvement' as I think it is interesting to 
look into reducing this pressure. This might be by squeezing more out of the 
{{SegmentIdTable}} bits (I'd like to followup on this with a benchmark) or 
revisiting the code paths from the {{Segment}} class.







[0] 
https://github.com/apache/jackrabbit-oak/blob/trunk/oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/Segment.java#L405



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