Wei Zhu created CASSANDRA-5342:
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Summary: ancestors are not cleared in SSTableMetadata after
compactions are done and old SSTables are removed
Key: CASSANDRA-5342
URL: https://issues.apache.org/jira/browse/CASSANDRA-5342
Project: Cassandra
Issue Type: Bug
Components: Core
Affects Versions: 1.2.2, 1.1.10
Reporter: Wei Zhu
We are using LCS and have total of 38000 SSTables for one CF. During LCS, there
could be over a thousand SSTable involved. All those SSTable IDs are stored in
ancestors field of SSTableMetatdata for the new table. In our case, it consumes
more than 1G of heap memory for those field. Put it in perspective, the
ancestors consume 2 - 3 times more memory than bloomfilter (fp = 0.1 by
default) in LCS.
We should remove those ancestors from SSTableMetadata after the compaction is
finished and the old SSTable is removed. It might be a big deal for Sized
Compaction since there are small number of SSTable involved. But it consumes a
lot of memory for LCS.
At least, we shouldn't load those ancestors to the memory during startup if the
files are removed.
I would love to contribute and provide patch. Please let me know how to start.
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