Returns true if expr
can be evaluated using only the output of plan
.
Returns true if expr
can be evaluated using only the output of plan
. This method
can be used to determine when it is acceptable to move expression evaluation within a query
plan.
For example consider a join between two relations R(a, b) and S(c, d).
canEvaluate(EqualTo(a,b), R)
returns true
where as canEvaluate(EqualTo(a,c), R)
returns
false
.
Name for this rule, automatically inferred based on class name.
Name for this rule, automatically inferred based on class name.
Pushes certain operations to both sides of a Union operator. Operations that are safe to pushdown are listed as follows. Union: Right now, Union means UNION ALL, which does not de-duplicate rows. So, it is safe to pushdown Filters and Projections through it. Once we add UNION DISTINCT, we will not be able to pushdown Projections.