alamb commented on code in PR #10963:
URL: https://github.com/apache/datafusion/pull/10963#discussion_r1645016269
##########
datafusion/optimizer/src/propagate_empty_relation.rs:
##########
@@ -400,6 +433,182 @@ mod tests {
assert_together_optimized_plan_eq(plan, expected)
}
+ #[test]
+ fn test_left_join_empty_left_table() -> Result<()> {
+ let left_table_scan = test_table_scan()?;
+ let left = LogicalPlanBuilder::from(left_table_scan)
+ .filter(Expr::Literal(ScalarValue::Boolean(Some(false))))?
+ .build()?;
+
+ let right_table_scan = test_table_scan_with_name("test2")?;
+ let right = LogicalPlanBuilder::from(right_table_scan).build()?;
+
+ let plan = LogicalPlanBuilder::from(left)
+ .join_using(
+ right,
+ JoinType::Left,
+ vec![Column::from_name("a".to_string())],
+ )?
+ .build()?;
+
+ let expected = "EmptyRelation";
+ assert_together_optimized_plan_eq(plan, expected)
+ }
+
+ #[test]
+ fn test_right_join_empty_right_table() -> Result<()> {
+ let left_table_scan = test_table_scan()?;
+ let left = LogicalPlanBuilder::from(left_table_scan).build()?;
+
+ let right_table_scan = test_table_scan_with_name("test2")?;
+ let right = LogicalPlanBuilder::from(right_table_scan)
+ .filter(Expr::Literal(ScalarValue::Boolean(Some(false))))?
+ .build()?;
+
+ let plan = LogicalPlanBuilder::from(left)
+ .join_using(
+ right,
+ JoinType::Right,
+ vec![Column::from_name("a".to_string())],
+ )?
+ .build()?;
+
+ let expected = "EmptyRelation";
+ assert_together_optimized_plan_eq(plan, expected)
+ }
+
+ #[test]
+ fn test_left_semi_join_empty_left_table() -> Result<()> {
+ let left_table_scan = test_table_scan()?;
+ let left = LogicalPlanBuilder::from(left_table_scan)
+ .filter(Expr::Literal(ScalarValue::Boolean(Some(false))))?
+ .build()?;
+
+ let right_table_scan = test_table_scan_with_name("test2")?;
+ let right = LogicalPlanBuilder::from(right_table_scan).build()?;
+
+ let plan = LogicalPlanBuilder::from(left)
+ .join_using(
+ right,
+ JoinType::LeftSemi,
+ vec![Column::from_name("a".to_string())],
+ )?
+ .build()?;
+
+ let expected = "EmptyRelation";
+ assert_together_optimized_plan_eq(plan, expected)
+ }
+
+ #[test]
+ fn test_left_semi_join_empty_right_table() -> Result<()> {
+ let left_table_scan = test_table_scan()?;
+ let left = LogicalPlanBuilder::from(left_table_scan).build()?;
+
+ let right_table_scan = test_table_scan_with_name("test2")?;
+ let right = LogicalPlanBuilder::from(right_table_scan)
+ .filter(Expr::Literal(ScalarValue::Boolean(Some(false))))?
+ .build()?;
+
+ let plan = LogicalPlanBuilder::from(left)
+ .join_using(
+ right,
+ JoinType::LeftSemi,
+ vec![Column::from_name("a".to_string())],
+ )?
+ .build()?;
+
+ let expected = "EmptyRelation";
+ assert_together_optimized_plan_eq(plan, expected)
+ }
+
+ #[test]
+ fn test_right_semi_join_empty_right_table() -> Result<()> {
+ let left_table_scan = test_table_scan()?;
+ let left = LogicalPlanBuilder::from(left_table_scan).build()?;
+
+ let right_table_scan = test_table_scan_with_name("test2")?;
+ let right = LogicalPlanBuilder::from(right_table_scan)
+ .filter(Expr::Literal(ScalarValue::Boolean(Some(false))))?
+ .build()?;
+
+ let plan = LogicalPlanBuilder::from(left)
+ .join_using(
+ right,
+ JoinType::RightSemi,
+ vec![Column::from_name("a".to_string())],
+ )?
+ .build()?;
+
+ let expected = "EmptyRelation";
+ assert_together_optimized_plan_eq(plan, expected)
+ }
+
+ #[test]
+ fn test_right_semi_join_empty_left_table() -> Result<()> {
+ let left_table_scan = test_table_scan()?;
+ let left = LogicalPlanBuilder::from(left_table_scan)
+ .filter(Expr::Literal(ScalarValue::Boolean(Some(false))))?
+ .build()?;
+
+ let right_table_scan = test_table_scan_with_name("test2")?;
+ let right = LogicalPlanBuilder::from(right_table_scan).build()?;
+
+ let plan = LogicalPlanBuilder::from(left)
+ .join_using(
+ right,
+ JoinType::RightSemi,
+ vec![Column::from_name("a".to_string())],
+ )?
+ .build()?;
+
+ let expected = "EmptyRelation";
+ assert_together_optimized_plan_eq(plan, expected)
+ }
+
+ #[test]
+ fn test_right_anti_join_empty_right_table() -> Result<()> {
Review Comment:
Can you please also add the negative cases ? Like test right
antijoin_empty_left_table and assert it wasn't rewritten?
##########
datafusion/optimizer/src/propagate_empty_relation.rs:
##########
@@ -400,6 +433,182 @@ mod tests {
assert_together_optimized_plan_eq(plan, expected)
}
+ #[test]
Review Comment:
I think having some end to end slt would be good too, but for these rules I
think having good unit tests are key as well
##########
datafusion/optimizer/src/propagate_empty_relation.rs:
##########
@@ -94,29 +94,62 @@ impl OptimizerRule for PropagateEmptyRelation {
Ok(Transformed::no(LogicalPlan::CrossJoin(join.clone())))
}
- LogicalPlan::Join(ref join) if join.join_type == Inner => {
+ LogicalPlan::Join(ref join) => {
// TODO: For Join, more join type need to be careful:
- // For LeftOuter/LeftSemi/LeftAnti Join, only the left side is
empty, the Join result is empty.
- // For LeftSemi Join, if the right side is empty, the Join
result is empty.
// For LeftAnti Join, if the right side is empty, the Join
result is left side(should exclude null ??).
- // For RightOuter/RightSemi/RightAnti Join, only the right
side is empty, the Join result is empty.
- // For RightSemi Join, if the left side is empty, the Join
result is empty.
// For RightAnti Join, if the left side is empty, the Join
result is right side(should exclude null ??).
// For Full Join, only both sides are empty, the Join result
is empty.
// For LeftOut/Full Join, if the right side is empty, the Join
can be eliminated with a Projection with left side
// columns + right side columns replaced with null values.
// For RightOut/Full Join, if the left side is empty, the Join
can be eliminated with a Projection with right side
// columns + left side columns replaced with null values.
let (left_empty, right_empty) =
binary_plan_children_is_empty(&plan)?;
- if left_empty || right_empty {
- return Ok(Transformed::yes(LogicalPlan::EmptyRelation(
- EmptyRelation {
+
Review Comment:
I double checked that this code faithfully implements the semantics in the
comments, and I did some mental review and verification to convince myself that
these semantics are correct
i wonder if @jackwener has a moment to double check too?
##########
datafusion/sqllogictest/test_files/subquery.slt:
##########
@@ -613,10 +613,7 @@ SELECT t1_id, t1_name FROM t1 WHERE EXISTS (SELECT * FROM
t2 WHERE t2_id = t1_id
query TT
explain SELECT t1_id, t1_name FROM t1 WHERE EXISTS (SELECT * FROM t2 WHERE
t2_id = t1_id limit 0)
----
-logical_plan
-01)LeftSemi Join: t1.t1_id = __correlated_sq_1.t2_id
-02)--TableScan: t1 projection=[t1_id, t1_name]
-03)--EmptyRelation
+logical_plan EmptyRelation
Review Comment:
> causing the entire join to be optimized out with the additional join types
now propagating emptyrelation.
I agree with your assesment. I think the `limit 0` means this plan is
better
In terms of preserving the test of the subquery rewrite I think it does
(otherwise it wouldn't be rewritten to a SEMI JOIN and thus the join couldn't
be removed)
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