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From cem <cayiro...@gmail.com>
Subject Cassandra 1.2 TTL histogram problem
Date Tue, 21 May 2013 20:43:47 GMT
Hi all,

I have a question about ticket
https://issues.apache.org/jira/browse/CASSANDRA-3442

Why does Cassandra single table compaction skips the keys that are in the
other sstables? Please correct if I am wrong.

I also dont understand why we have this line in worthDroppingTombstones
method:

double remainingColumnsRatio = ((double) columns) / (sstable.
getEstimatedColumnCount<http://grepcode.com/file/repo1.maven.org/maven2/org.apache.cassandra/cassandra-all/1.2.2/org/apache/cassandra/io/sstable/SSTableReader.java#SSTableReader.getEstimatedColumnCount%28%29>
().count<http://grepcode.com/file/repo1.maven.org/maven2/org.apache.cassandra/cassandra-all/1.2.2/org/apache/cassandra/utils/EstimatedHistogram.java#EstimatedHistogram.count%28%29>
() * sstable.getEstimatedColumnCount<http://grepcode.com/file/repo1.maven.org/maven2/org.apache.cassandra/cassandra-all/1.2.2/org/apache/cassandra/io/sstable/SSTableReader.java#SSTableReader.getEstimatedColumnCount%28%29>
().mean<http://grepcode.com/file/repo1.maven.org/maven2/org.apache.cassandra/cassandra-all/1.2.2/org/apache/cassandra/utils/EstimatedHistogram.java#EstimatedHistogram.mean%28%29>
());

remainingColumnsRatio  is always *0 *in my case and the droppableRatio
 is *0.9.
Cassandra skips all sstables which are already expired.*

This line was introduced by
https://issues.apache.org/jira/browse/CASSANDRA-4022.

Best Regards,
Cem

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