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  1. IMPALA
  2. IMPALA-5911

Grouping aggregations with having conjuncts and Serialize()/Finalize() functions uses excessive expr memory

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: Impala 2.10.0
    • Fix Version/s: Impala 2.11.0
    • Component/s: Backend
    • Labels:
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      Description

      The loop in GetRowsFromPartition() invokes Finalize()/Serialize() on all of the rows in output_partition_, which may allocate local allocations in output_partition_->agg_fn_evals. These are not cleared out until the partition is destroyed.

      If the having conjuncts are very select this can result in a lot of excess memory. E.g. the following query results in a lot of non-buffer-pool memory overhead:

      select l_orderkey, min(l_comment) from tpch_parquet.lineitem group by l_orderkey having min(l_comment) like '%slow dolphins%' order by l_orderkey
      

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              • Assignee:
                tarmstrong Tim Armstrong
                Reporter:
                tarmstrong Tim Armstrong
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                • Created:
                  Updated:
                  Resolved: