ColumnStat¶

Creating Instance¶

ColumnStat takes the following to be created:

• Distinct Count (number of distinct values)
• Minimum Value
• Maximum Value
• Null Count (number of null values)
• Average length of the values (for fixed-length types, this should be a constant)
• Maximum length of the values (for fixed-length types, this should be a constant)
• Histogram
• 2

ColumnStat is created when:

• CatalogColumnStat is requested to toPlanStat
• Range logical operator is requested to computeStats
• EstimationUtils is requested to nullColumnStat
• JoinEstimation is requested to computeByNdv, computeByHistogram
• UnionEstimation is requested to computeMinMaxStats, computeNullCountStats
• CommandUtils is requested to rowToColumnStat

Converting to CatalogColumnStat¶

toCatalogColumnStat(
  colName: String,
  dataType: DataType): CatalogColumnStat

toCatalogColumnStat converts this ColumnStat to a CatalogColumnStat.

toCatalogColumnStat is used when:

• PruneHiveTablePartitions logical optimization is requested to updateTableMeta
• AnalyzeColumnCommand logical command is requested to analyzeColumnInCatalog
• PruneFileSourcePartitions logical optimization is executed