[jira] [Created] (OAK-1031) SegmentMK: Fewer segment lookups

["Jukka Zitting (JIRA)" <ji...@apache.org>]

Jukka Zitting created OAK-1031:
----------------------------------

             Summary: SegmentMK: Fewer segment lookups
                 Key: OAK-1031
                 URL: https://issues.apache.org/jira/browse/OAK-1031
             Project: Jackrabbit Oak
          Issue Type: Sub-task
          Components: core
            Reporter: Jukka Zitting
            Priority: Minor


The SegmentMK uses record references composed of a segment UUID and an offset within that segment. When accessing a record, the normal pattern is to first look up the segment using the UUID and then read the data from that segment.

Unfortunately it looks like all those segment lookups take up a notable percentage of the time spent reading data in the SegmentMK, so it would be good if we could avoid at least some of those lookups.

Given the locality of reference that the SegmentMK design tries to maximise, achieving that goal should be easy. In practice most record references point to other records in the same segment, so if we keep track of the segment we're currently accessing, we can in most cases avoid the extra lookups.

Some of this work is already implemented, especially for accessing property values, but other pieces are still missing. This issue exist to track the remaining work.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira