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From "Tey Kar Shiang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-2401) getColumnFamily() return null, which is not checked in ColumnFamilyStore.java scan() method, causing Timeout Exception in query
Date Wed, 30 Mar 2011 02:18:05 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-2401?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13012821#comment-13012821
] 

Tey Kar Shiang commented on CASSANDRA-2401:
-------------------------------------------

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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