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From "Michael Andre Pearce (IG) (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HAWQ-1464) JDBC-PXF - support concurrency limiting
Date Thu, 11 May 2017 22:28:04 GMT
Michael Andre Pearce (IG) created HAWQ-1464:

             Summary: JDBC-PXF - support concurrency limiting
                 Key: HAWQ-1464
                 URL: https://issues.apache.org/jira/browse/HAWQ-1464
             Project: Apache HAWQ
          Issue Type: Sub-task
          Components: PXF
            Reporter: Michael Andre Pearce (IG)
            Assignee: Vineet Goel

The external table definition doesn't limit how many concurrent queries can be executed on
the remote server. It would be pretty simple to create a single external table using PXF JDBC
that would issue thousands of concurrent queries to a single source database when doing a
single SELECT in HAWQ.
Initially, we should add a max_queries variable to the configuration file that I'm suggesting,
that will reject queries from proceeding when a greater number of PXF instances are being
requested than the max_queries variable. Longer term, we should implement a queueing system
so we can support external tables that partitions data from the source at a very small grain
but without killing the source database.

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