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  1. Spark
  2. SPARK-26088

DataSourceV2 should expose row count and attribute statistics

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    Details

    • Type: Improvement
    • Status: Open
    • Priority: Minor
    • Resolution: Unresolved
    • Affects Version/s: 2.3.0
    • Fix Version/s: None
    • Component/s: SQL
    • Labels:
      None

      Description

      During investigation of CBO and DataSourceV2 we found, that

      org.apache.spark.sql.sources.v2.reader.Statistics
      

      misses attribute/column statistics and that

      DataSourceV2Relation#computeStats
      

      wraps

      org.apache.spark.sql.sources.v2.reader.Statistics
      

      into

      org.apache.spark.sql.catalyst.plans.logical.Statistics
      

      without forwarding the optional rowCount if present.

      However rowCount and attributeStats are used during CBO e.g. in JoinEstimation and AggregateEstimation.

      We propose that:

      • org.apache.spark.sql.sources.v2.reader.Statistics mirrors org.apache.spark.sql.catalyst.plans.logical.Statistics
      • DataSourceV2Relation forwards all the information to be available during CBO

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              • Assignee:
                Unassigned
                Reporter:
                mju Martin Junghanns
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                Dates

                • Created:
                  Updated: