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Radim Kolar commented on CASSANDRA-5727:
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You are missing 3 important points. There is no need to read lvldb source code,
just read log file and you will notice differences in compaction, which
contribute to speedup.
I implemented lvldb 3 times. First into HDFS - where metadata are stored into
path, second version was improvement of cassandra code, and 3rd version is
improved version of current google record based backend, which is leveldb based
with modifications allowing it run without filesystem and network part removed
+ 2 small performance tunings with major effect.
You are right about concurrent compactions and non blocking writes for L0.
K, you wanted hint, so here it is: Compare L0 in C 2.0 and leveldb.
> Evaluate default LCS sstable size
> ---------------------------------
>
> Key: CASSANDRA-5727
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5727
> Project: Cassandra
> Issue Type: Task
> Components: Core
> Reporter: Jonathan Ellis
> Assignee: Daniel Meyer
>
> What we're not sure about is the effect on compaction efficiency --
> larger files mean that each level contains more data, so reads will
> have to touch less sstables, but we're also compacting less unchanged
> data when we merge forward.
> So the question is, how big can we make the sstables to get the benefits of
> the
> first effect, before the second effect starts to dominate?
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