EstimationUtils¶

EstimationUtils is...FIXME

=== [[getOutputSize]] getOutputSize Method

[source, scala]¶

getOutputSize( attributes: Seq[Attribute], outputRowCount: BigInt, attrStats: AttributeMap[ColumnStat] = AttributeMap(Nil)): BigInt

getOutputSize...FIXME

NOTE: getOutputSize is used when...FIXME

=== [[nullColumnStat]] nullColumnStat Method

[source, scala]¶

nullColumnStat(dataType: DataType, rowCount: BigInt): ColumnStat¶

nullColumnStat...FIXME

NOTE: nullColumnStat is used exclusively when JoinEstimation is requested to estimateInnerOuterJoin for LeftOuter and RightOuter joins.

=== [[rowCountsExist]] Checking Availability of Row Count Statistic -- rowCountsExist Method

[source, scala]¶

rowCountsExist(plans: LogicalPlan*): Boolean¶

rowCountsExist is positive (i.e. true) when every logical plan (in the input plans) has estimated number of rows (aka row count) statistic computed.

Otherwise, rowCountsExist is negative (i.e. false).

NOTE: rowCountsExist uses LogicalPlanStats to access the estimated statistics and query hints of a logical plan.

rowCountsExist is used when:

• AggregateEstimation is requested to estimate statistics and query hints of a Aggregate logical operator

• JoinEstimation is requested to estimate statistics and query hints of a Join logical operator (regardless of the join type)

• ProjectEstimation is requested to estimate statistics and query hints of a Project logical operator