Class: Veritas::Optimizer::Algebra::Projection::EmptyOperand

Inherits:
Veritas::Optimizer::Algebra::Projection show all
Defined in:
lib/veritas/optimizer/algebra/projection.rb

Overview

Optimize when the operand is Empty

Constant Summary

Constants inherited from Veritas::Optimizer

Noop, VERSION

Instance Attribute Summary

Attributes inherited from Relation::Operation::Unary

#header

Attributes included from Function::Unary

#operand

Attributes inherited from Veritas::Optimizer

#operation

Instance Method Summary collapse

Methods inherited from Relation::Operation::Unary

#initialize

Methods included from Function::Unary

#initialize

Methods inherited from Veritas::Optimizer

chain, #initialize

Constructor Details

This class inherits a constructor from Veritas::Optimizer::Relation::Operation::Unary

Instance Method Details

#optimizable? ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Test if the operand is empty

Returns:

  • (Boolean) 


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# File 'lib/veritas/optimizer/algebra/projection.rb', line 100

def optimizable?
  operand.kind_of?(Veritas::Relation::Empty)
end

#optimize ⇒ Empty

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Return a new Empty relation with the operation’s headers

Returns:

  • (Empty) 


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# File 'lib/veritas/optimizer/algebra/projection.rb', line 109

def optimize
  Veritas::Relation::Empty.new(header, operation)
end