org.apache.spark.sql.catalyst.optimizer
CheckCartesianProducts
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package optimizer
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
- canEvaluate(EqualTo(a,c), R) returns false
- canEvaluate(Literal(1), R) returns true as literals CAN be evaluated on any plan
Returns true iff expr could be evaluated as a condition within join.
Returns true iff expr could be evaluated as a condition within join.
Check if a join is a cartesian product.
Check if a join is a cartesian product. Returns true if there are no join conditions involving references from both left and right.
Name for this rule, automatically inferred based on class name.
Name for this rule, automatically inferred based on class name.
Check if there any cartesian products between joins of any type in the optimized plan tree. Throw an error if a cartesian product is found without an explicit cross join specified. This rule is effectively disabled if the CROSS_JOINS_ENABLED flag is true.
This rule must be run AFTER the ReorderJoin rule since the join conditions for each join must be collected before checking if it is a cartesian product. If you have SELECT * from R, S where R.r = S.s, the join between R and S is not a cartesian product and therefore should be allowed. The predicate R.r = S.s is not recognized as a join condition until the ReorderJoin rule.