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  1. IMPALA
  2. IMPALA-8809

Refresh a subset of partitions for ACID tables

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    Details

    • Type: Improvement
    • Status: In Progress
    • Priority: Critical
    • Resolution: Unresolved
    • Affects Version/s: Impala 3.3.0
    • Fix Version/s: None
    • Component/s: None
    • Labels:
    • Epic Color:
      ghx-label-2

      Description

      Enhancing REFRESH logic to handle ACID tables was covered by this change: https://issues.apache.org/jira/browse/IMPALA-8600
      Basically each user initiated REFRESH PARTITION is rejected meanwhile the REFRESH_PARTITION event in event processor are actually doing a full table load for ACID tables.

      There is room for improvement: When a full table refresh is being executed on an ACID table we can have 2 scenarios:

      • If there was some schema changes then reload the full table. Identify such a scenario should be possible by checking the table-level writeId. However, there is a bug in Hive that it doesn't update that field for partitioned tables (https://issues.apache.org/jira/browse/HIVE-22062). This would be the desired way but could also be workarounded by checking other fields lik lastDdlChanged or such.
      • If a full table refresh is not needed then we should fetch the partition-level writeIds and reload only the ones that are out-of-date locally.

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              • Assignee:
                gaborkaszab Gabor Kaszab
                Reporter:
                gaborkaszab Gabor Kaszab
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                Dates

                • Created:
                  Updated: