[GitHub] spark pull request #14971: [SPARK-17410] [SPARK-17284] Move Hive-generated S...

[cloud-fan <gi...@git.apache.org>]

Github user cloud-fan commented on a diff in the pull request:

    https://github.com/apache/spark/pull/14971#discussion_r95975787
  
    --- Diff: sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveClientImpl.scala ---
    @@ -378,6 +380,50 @@ private[hive] class HiveClientImpl(
     
           val properties = Option(h.getParameters).map(_.asScala.toMap).orNull
     
    +      // Hive-generated Statistics are also recorded in ignoredProperties
    +      val ignoredProperties = scala.collection.mutable.Map.empty[String, String]
    +      properties.collect {
    +        case (key, value) if HiveStatisticsProperties.contains(key) =>
    +          ignoredProperties += (key -> value)
    +      }
    +
    +      val excludedTableProperties = HiveStatisticsProperties ++ Set(
    +        // The property value of "comment" is moved to the dedicated field "comment"
    +        "comment",
    +        // For EXTERNAL_TABLE, the table properties has a particular field "EXTERNAL". This is added
    +        // in the function toHiveTable.
    +        "EXTERNAL"
    +      )
    +
    +      val filteredProperties = properties.filterNot {
    +        case (key, _) => excludedTableProperties.contains(key)
    +      }
    +      val comment = properties.get("comment")
    +
    +      val totalSize = properties.get(StatsSetupConst.TOTAL_SIZE).map(BigInt(_))
    +      val rawDataSize = properties.get(StatsSetupConst.RAW_DATA_SIZE).map(BigInt(_))
    +      val rowCount = properties.get(StatsSetupConst.ROW_COUNT).map(BigInt(_)) match {
    +        case Some(c) if c >= 0 => Some(c)
    +        case _ => None
    +      }
    +      // TODO: check if this estimate is valid for tables after partition pruning.
    +      // NOTE: getting `totalSize` directly from params is kind of hacky, but this should be
    +      // relatively cheap if parameters for the table are populated into the metastore.
    +      // Currently, only totalSize, rawDataSize, and row_count are used to build the field `stats`
    +      // TODO: stats should include all the other two fields (`numFiles` and `numPartitions`).
    +      // (see StatsSetupConst in Hive)
    +      val stats =
    +        // When table is external, `totalSize` is always zero, which will influence join strategy
    +        // so when `totalSize` is zero, use `rawDataSize` instead. When `rawDataSize` is also zero,
    +        // return None. Later, we will use the other ways to estimate the statistics.
    +        if (totalSize.isDefined && totalSize.get > 0L) {
    +          Some(Statistics(sizeInBytes = totalSize.get, rowCount = rowCount))
    +        } else if (rawDataSize.isDefined && rawDataSize.get > 0) {
    +          Some(Statistics(sizeInBytes = rawDataSize.get, rowCount = rowCount))
    +        } else {
    +          None
    --- End diff --
    
    shall we respect `rowCount` in this case?


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