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  1. Apache Drill
  2. DRILL-5830

Resolve regressions to MapR DB from DRILL-5546

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 1.12.0
    • Fix Version/s: 1.12.0
    • Component/s: None
    • Labels:
      None

      Description

      DRILL-5546 added a number of fixes for empty batches. One part of the fix was for HBase. Key changes:

      • Add code to expand wildcards in the planner. (i.e. SELECT *)
      • Remove support for wildcards in the HBase record reader.

      As noted in DRILL-5775, this change had the effect of breaking support for MapR-DB binary (which is API compatible with HBase.) DRILL-5775 does this by expanding wildcards in the planner for MapR DB as was done for HBase in DRILL-5546.

      Unfortunately, this change introduced other regressions into the code as described by DRILL-5706.

      Investigation of those issues revealed that we should back out the original DRILL-5546 changes and go down a different route.

      As it turns out, HBase already had a project push-down rule that expanded wildcards. However, that rule didn't work correctly some of the time. DRILL-5546 fixed that bug, ensuring that wildcards are expanded (at least in the cases tested for this ticket.)

      The actual issue turned out to be a bug in the RecordBatchLoader class which did not consider map contents when detecting schema change. As a result, results like (row_key, cf{}) were treated the same as (row_key, cf{mycol}) and the actual data colums were discarded, but randomly depending on batch arrival order.

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              • Assignee:
                Paul.Rogers Paul Rogers
                Reporter:
                Paul.Rogers Paul Rogers
                Reviewer:
                Arina Ielchiieva
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                • Created:
                  Updated:
                  Resolved: