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  1. IMPALA
  2. IMPALA-12647

Add Hive compatible way to get modified row count in DMLs (HS2)

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    • New Feature
    • Status: Open
    • Major
    • Resolution: Unresolved
    • None
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    • Clients
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    • ghx-label-2

    Description

      e,.g after
      insert into t values (1);
      print "modified 1 rows(s)"

      Hive and Impala implemented this in incompatible ways using different HS2 "dialects":

      • HIVE-14388 added support using TGetOperationStatusResp.numModifiedRows
      • IMPALA-7290 added support using TCloseImpalaOperationResp,TDmlResult

      https://github.com/apache/hive/blob/fd92b3926393f0366b87cd55d5a0ad27968f18db/service-rpc/if/TCLIService.thrift#L1120
      https://github.com/apache/impala/blob/4114fe8db6ec80b2e1679e946555f91ab7043f2e/common/thrift/ImpalaService.thrift#L966

      The Impala patch is newer (probably we didn't know about the Hive solution?), on the other side it is based on a much older solution in Beeswax. The Impala solution is also more "advanced" and contains extra information relevant in Kudu upserts/inserts.

      Currently impala-shell uses the Impala solution while in Hive compatible strict HS2 mode it doesn't return modified row count.

      impyla doesn't support modified row count: https://github.com/cloudera/impyla/issues/302
      There is an extension function that parses Kudu related row counts from the profile:
      https://github.com/cloudera/impyla/blob/76f0ba3221e1ff26037e36afbe4a5591168157ce/impala/hiveserver2.py#L205

      Ideally there would be a solution supported by both components and clients wouldn't need to adapt to specific dialects.

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              noemi Noemi Pap-Takacs
              csringhofer Csaba Ringhofer
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                Created:
                Updated: