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https://issues.apache.org/jira/browse/CASSANDRA-6348?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13830415#comment-13830415
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Alex Liu commented on CASSANDRA-6348:
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If there is data filtering, for cql query, the total number of index columns
needed is unknown, and it's not directly related to the limit clause, so we
can't calculate it based on limit clause. Set it to a magic number which is
large enough but not too large is a viable solution.
> TimeoutException throws if Cql query allows data filtering and index is too
> big and it can't find the data in base CF after filtering
> --------------------------------------------------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-6348
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6348
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Reporter: Alex Liu
> Assignee: Alex Liu
> Attachments: 6348.txt
>
>
> If index row is too big, and filtering can't find the match Cql row in base
> CF, it keep scanning the index row and retrieving base CF until the index row
> is scanned completely which may take too long and thrift server returns
> TimeoutException. This is one of the reasons why we shouldn't index a column
> if the index is too big.
> Multiple indexes merging can resolve the case where there are only EQUAL
> clauses. (CASSANDRA-6048 addresses it).
> If the query has none-EQUAL clauses, we still need do data filtering which
> might lead to timeout exception.
> We can either disable those kind of queries or WARN the user that data
> filtering might lead to timeout exception or OOM.
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