Class OutputWidthExpression

Direct Known Subclasses:
OutputWidthExpression.FixedLenExpr, OutputWidthExpression.FunctionCallExpr, OutputWidthExpression.IfElseWidthExpr, OutputWidthExpression.VarLenReadExpr

public abstract class OutputWidthExpression extends Object
OutputWidthExpressions are used to capture the information required to calculate the width of the output produced by a variable-width expression. This is used by the ProjectMemoryManager to calculate output-widths of the expressions being projected. Expressions in Drill are represented as a tree of LogicalExpression. During the setup phase, the OutputWidthVisitor walks the tree of LogicalExpressions and reduces it to a tree of OutputWidthExpressions. In the execution phase, the OutputWidthVisitor walks the tree of OutputWidthExpressions and reduces it to a fixed output-width by using the average-sizes of incoming columns obtained from the RecordBatchSizer
  • Constructor Details

    • OutputWidthExpression

      public OutputWidthExpression()