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https://issues.apache.org/jira/browse/CASSANDRA-5682?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13859121#comment-13859121
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Rao commented on CASSANDRA-5682:
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Question: we are seeing some performance issues with some queries.. (only with
specific inputs). The first query takes around 10sec, the second query comes
back instantly. The column "routeoffer" has a secondary index. How can we check
if we have a similar issues described in the ticket OR could it be some thing
else? tried to repair and rebuild index, but it did not fix the issue.
cqlsh:topology> SELECT count(*) FROM ManagedResource WHERE routeoffer='JMETER'
ALLOW FILTERING;
count
-------
137
cqlsh:topology> SELECT count(*) FROM ManagedResource WHERE routeoffer='DEFAULT'
ALLOW FILTERING;
count
-------
161
> When the Cassandra delete keys in secondary Index?
> --------------------------------------------------
>
> Key: CASSANDRA-5682
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5682
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Affects Versions: 2.0.1
> Environment: normal x86 PC (i3 CPU + 4GB ram) + Ubuntu 12.04
> Reporter: YounwooKim
> Priority: Minor
>
> How can i reduce the size of secondary index?
> Obviously, I delete many keys, and tried flush, compact, cleanup,
> rebuild_index using nodetool. However, i can't reduce the size of secondary
> index. ( Of course, the size of table(Primary key) is reduced. )
> Therefore, I found out the hint from the Cassandra source code, and I guess a
> feature of secondary index deletion.
> 1) When I request deletion of key, and the key is in the sstable(not in the
> memtable), the Cassandra doesn't insert the tombstone to the sstable for
> secondary index.( Unlike the table )
> ( from AbstractSimpleColumnSecondaryIndex.delete() function. )
> 2) After scaning the secondary index, the tombstone is maded in secondary
> index.
> ( from KeysSearcher.getIndexedIterator() function. It is called by index scan
> verb. )
> 3) Cleanup command in nodetool is used to delete out of range keys. ( Cleanup
> command don't care about deleted keys )
> ( from CompactionManager.doCleanupCompaction() function. )
> After this, I scan deleted keys using 'Where' clause, and I can reduce the
> size of secondary index. I think that it is only one way to reduce the size
> of secondary index.
> Is this a correct conclusion? I can't found related articles and other
> methods.
> I think that the Cassandra needs the compaction function for secondary index .
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