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https://issues.apache.org/jira/browse/NIFI-5303?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16509825#comment-16509825
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ASF GitHub Bot commented on NIFI-5303:
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GitHub user mattyb149 opened a pull request:
https://github.com/apache/nifi/pull/2788
NIFI-5303: Fixed QueryDatabaseTable to work with DB2
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You can merge this pull request into a Git repository by running:
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Alternatively you can review and apply these changes as the patch at:
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This closes #2788
----
commit 926b91d2b0f83a6dfbca4aee415d2842a0705291
Author: Matthew Burgess <mattyb149@...>
Date: 2018-06-12T16:26:19Z
NIFI-5303: Fixed QueryDatabaseTable to work with DB2
----
> QueryDatabaseTable encounters errors when processing rows in DB2
> ----------------------------------------------------------------
>
> Key: NIFI-5303
> URL: https://issues.apache.org/jira/browse/NIFI-5303
> Project: Apache NiFi
> Issue Type: Improvement
> Components: Extensions
> Reporter: Matt Burgess
> Assignee: Matt Burgess
> Priority: Major
>
> Due to a bug in the DB2 driver, if next() is called twice on a result set
> when there are no more rows, it will throw an exception to that effect.
> Supposedly you can set allowNextOnExhaustedResultSet=1 on the JDBC URL or
> connection properties, but in my testing that has not alleviated the problem.
> ExecuteSQL retrieves the entire result set at once, so the first call to
> next() when all rows have been fetched correctly returns false, and
> processing continues. However in QueryDatabaseTable, due to Max Fragments and
> Max Records Per Flowfile properties, it is possible that there are still rows
> remaining, but the current code cannot tell the difference and will try again
> until no rows have been fetched.
> For example, in a table with 5 rows, with Max Rows Per FlowFile set to 4, the
> first pass will correctly process 4 rows. The second pass will process 1 and
> next() will return false. Then another pass is made to see if there are any
> more results, so the second call to next() will produce the aforementioned
> error.
> Additional logic should be added to QueryDatabaseTable to determine whether
> all rows have been fetched. For example, if neither Max Fragments or Max Rows
> Per Flowfile have been set, then the first pass will retrieve all rows and
> the code does not have to check again. If Max Rows Per Flowfile has been set
> and the number of processed rows is less than that, then all rows have been
> processed and the code does not have to check again. Otherwise if exactly the
> "right" number of rows have been processed, then the next pass will call
> next() to return false, and since zero records have been processed on that
> pass, the code will continue as it originally did.
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