[IMPALA-6626] Failure to assign dictionary predicates should not result in query failure - testing needed

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: Impala 2.9.0, Impala 2.10.0, Impala 2.11.0
• Component/s: Frontend
• Epic Color: ghx-label-8
• Assignee: Unassigned
• Reporter: Alexander Behm
• Created: 08/Mar/18 00:18
• Updated: 13/May/19 22:52

Description

Assigning dictionary predicates to Parquet scans may involve evaluation of expressions in the BE which could fail for various reasons. Such failures should lead to non-assignment of dictionary predicates but not to query failure.

See HdfsScanNode:

private void addDictionaryFilter(...) {
...
    try {
      if (analyzer.isTrueWithNullSlots(conjunct)) return;
    } catch (InternalException e) { <--- does not handle Exception which will cause query to fail
      // Expr evaluation failed in the backend. Skip this conjunct since we cannot
      // determine whether it is safe to apply it against a dictionary.
      LOG.warn("Skipping dictionary filter because backend evaluation failed: "
          + conjunct.toSql(), e);
      return;
    }
}

Issue Links

• is blocked by: IMPALA-6617 Preconditions.checkState(val.getColValsSize() == 1); in EvalExprWithoutRow()