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  1. MariaDB MaxScale
  2. MXS-1411

error : (46) [maxrows] Received data from the backend although we were expecting nothing.

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    Details

    • Type: Bug
    • Status: Closed (View Workflow)
    • Priority: Critical
    • Resolution: Fixed
    • Affects Version/s: 2.1.7
    • Fix Version/s: 2.1.8
    • Component/s: maxrows
    • Labels:
      None

      Description

      One may get the following error from maxrows filter in MaxScale 2.1.7 with otherwise usual load:

      2017-09-13 14:13:13 error : (46) [maxrows] Received data from the backend although we were expecting nothing.

      Relevant parts of configuration file are:

      [maxscale]
      threads=4
      ...
      [Galera Monitor]
      type=monitor
      module=galeramon
      servers=N1, N2, N3
      ...
      [Splitter Service]
      type=service
      router=readwritesplit
      servers=N1, N2, N3
      ...
      max_slave_connections=100%
      connection_timeout=5400
      disable_sescmd_history=true
      max_sescmd_history=5
      strict_multi_stmt=false
      filters=Hint | MaxRows
       
      [Hint]
      type=filter
      module=hintfilter
       
      [MaxRows]
      type=filter
      module=maxrows
      max_resultset_rows=300000
      max_resultset_size=1T
      max_resultset_return=error
      ...
      

      Hint filter is needed to route SELECT .. FOR UPDATE to master. Everything works without problems when MaxRows filter is not involved.

      It would be great to document explicitly when this kind of error may happen and, if possible, prevent it.

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            Assignee:
            Massimiliano Pinto Massimiliano Pinto (Inactive)
            Reporter:
            valerii Valerii Kravchuk
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              Dates

              Created:
              Updated:
              Resolved: