Package io.trino.sql.planner.iterative.rule

Class MergeProjectWithValues

java.lang.Object
io.trino.sql.planner.iterative.rule.MergeProjectWithValues
All Implemented Interfaces:
Rule<ProjectNode>
public class MergeProjectWithValues extends Object implements Rule<ProjectNode>
Transforms: 

 - Project
      a <- a
      d <- b
      e <- f(b)
      f <- 1
      - Values(a, b, c)
          expr_a_1, expr_b_1, expr_c_1
          expr_a_2, expr_b_2, expr_c_2
into: 

 - Values (a, d, e, f)
      expr_a_1, expr_b_1, f(expr_b_1), 1
      expr_a_2, expr_b_2, f(expr_b_2), 1
Note: this rule does not fire if ValuesNode contains a non-deterministic expression and it is referenced more than once in ProjectNode's assignments. This is to prevent incorrect results in the following case: 

 - project
      row <- ROW(rand, rand)
      - Values(rand)
          rand()
The expected result of the projection is a row with both fields equal. However, if the non-deterministic expression rand() was inlined, we would get two independent random values.