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T Jake Luciani commented on CASSANDRA-5936: ------------------------------------------- [~mericsson] Have you looked at all at promoting any L0 sstable to a level with no overlaps? LevelDB does this and I think it would give LCS a lot more breathing room before it starts hitting the wall. It would also promote more cross level parallel compactions. > Improve the way we pick L0 compaction candidates > ------------------------------------------------ > > Key: CASSANDRA-5936 > URL: https://issues.apache.org/jira/browse/CASSANDRA-5936 > Project: Cassandra > Issue Type: Improvement > Components: Core > Reporter: Marcus Eriksson > Assignee: Marcus Eriksson > Fix For: 2.1 > > > We could improve the way we pick compaction candidates in level 0 in LCS. > The most common way for us to get behind on compaction is after repairs, we > should exploit the fact that the streamed sstables are most often very narrow > in range since the other nodes in the ring will have a similar > sstable-range-distribution. We should in theory be able to do 10 concurrent > compactions involving L1 - ie, partition L0 in buckets defined by the > sstables in L1 to only keep one L1 SSTable busy for every compaction (be it > L1 to L2 or L0 to L1). > we will need some heuristics on when to select candidates from the buckets > and when to do it the old way (since L0 sstables can span several L1 sstables) -- This message was sent by Atlassian JIRA (v6.1#6144)