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From "Carl Yeksigian (JIRA)" <>
Subject [jira] [Created] (CASSANDRA-7409) Allow multiple overlapping sstables in L1
Date Tue, 17 Jun 2014 18:03:02 GMT
Carl Yeksigian created CASSANDRA-7409:

             Summary: Allow multiple overlapping sstables in L1
                 Key: CASSANDRA-7409
             Project: Cassandra
          Issue Type: Improvement
            Reporter: Carl Yeksigian
            Assignee: Carl Yeksigian

Currently, when a normal L0 compaction takes place (not STCS), we take up to MAX_COMPACTING_L0
L0 sstables and all of the overlapping L1 sstables and compact them together. If we didn't
have to deal with the overlapping L1 tables, we could compact a higher number of L0 sstables
together into a set of non-overlapping L1 sstables.

This could be done by delaying the invariant that L1 has no overlapping sstables. Going from
L1 to L2, we would be compacting fewer sstables together which overlap.

When reading, we will not have the same one sstable per level (except L0) guarantee, but this
can be bounded (once we have too many sets of sstables, either compact them back into the
same level, or compact them up to the next level).

This could be generalized to allow any level to be the maximum for this overlapping strategy.

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