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  1. Apache NiFi
  2. NIFI-2881

Allow Database Fetch processor(s) to accept incoming flow files and use Expression Language

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    Details

    • Type: Improvement
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 1.2.0
    • Component/s: Extensions
    • Labels:
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      Description

      The QueryDatabaseTable and GenerateTableFetch processors do not allow Expression Language to be used in the properties, mainly because they also do not allow incoming connections. This means if the user desires to fetch from multiple tables, they currently need one instance of the processor for each table, and those table names must be hard-coded.

      To support the same capabilities for multiple tables and more flexible configuration via Expression Language, these processors should have properties that accept Expression Language, and GenerateTableFetch should accept (optional) incoming connections.

      Conversation about the behavior of the processors is welcomed and encouraged. For example, if an incoming flow file is available, do we also still run the incremental fetch logic for tables that aren't specified by this flow file, or do we just do incremental fetching when the processor is scheduled but there is no incoming flow file. The latter implies a denial-of-service could take place, by flooding the processor with flow files and not letting it do its original job of querying the table, keeping track of maximum values, etc.

      This is likely a breaking change to the processors because of how state management is implemented. Currently since the table name is hard coded, only the column name comprises the key in the state. This would have to be extended to have a compound key that represents table name, max-value column name, etc.

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              • Assignee:
                mattyb149 Matt Burgess
                Reporter:
                mattyb149 Matt Burgess
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