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https://issues.apache.org/jira/browse/CASSANDRA-2401?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13012821#comment-13012821
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Tey Kar Shiang commented on CASSANDRA-2401:
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Hi,
New finding here:
For the 0-column data, it is because it is never read from the file. As I step
through the line, here it returns -1 position from
org.apache.cassandra.io.sstable.SSTableReader.java::getPosition(DecoratedKey
decoratedKey, Operator op), line 448 (bf.isPresent(decoratedKey.key) is
returning false) - key is missing.
There seem to be a missing record which is indexed or indexed column itself not
updated when the record is removed (?).
As for the data return with 0-column, simply because a container is always
created (final ColumnFamily returnCF = ColumnFamily.create(metadata)) and
returned from getTopLevelColumns even if there is no read taken.
> getColumnFamily() return null, which is not checked in ColumnFamilyStore.java
> scan() method, causing Timeout Exception in query
> -------------------------------------------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-2401
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2401
> Project: Cassandra
> Issue Type: Bug
> Affects Versions: 0.7.4
> Environment: Hector 0.7.0-28, Cassandra 0.7.4, Windows 7, Eclipse
> Reporter: Tey Kar Shiang
>
> ColumnFamilyStore.java, line near 1680, "ColumnFamily data =
> getColumnFamily(new QueryFilter(dk, path, firstFilter))", the data is
> returned null, causing NULL exception in "satisfies(data, clause, primary)"
> which is not captured. The callback got timeout and return a Timeout
> exception to Hector.
> The data is empty, as I traced, I have the the columns Count as 0 in
> removeDeletedCF(), which return the null there. (I am new and trying to
> understand the logics around still). Instead of crash to NULL, could we
> bypass the data?
> About my test:
> A stress-test program to add, modify and delete data to keyspace. I have 30
> threads simulate concurrent users to perform the actions above, and do a
> query to all rows periodically. I have Column Family with rows (as File) and
> columns as index (e.g. userID, fileType).
> No issue on the first day of test, and stopped for 3 days. I restart the test
> on 4th day, 1 of the users failed to query the files (timeout exception
> received). Most of the users are still okay with the query.
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