libenchao commented on code in PR #2848: URL: https://github.com/apache/calcite/pull/2848#discussion_r915379084
########## core/src/main/java/org/apache/calcite/rel/rules/SemiJoinRule.java: ########## @@ -42,14 +43,18 @@ /** * Planner rule that creates a {@code SemiJoin} from a * {@link org.apache.calcite.rel.core.Join} on top of a - * {@link org.apache.calcite.rel.logical.LogicalAggregate}. + * {@link org.apache.calcite.rel.logical.LogicalAggregate} or + * on a {@link org.apache.calcite.rel.RelNode} which is + * unique for join's right keys. */ public abstract class SemiJoinRule extends RelRule<SemiJoinRule.Config> implements TransformationRule { private static boolean isJoinTypeSupported(Join join) { final JoinRelType type = join.getJoinType(); - return type == JoinRelType.INNER || type == JoinRelType.LEFT; + return type == JoinRelType.INNER + || type == JoinRelType.LEFT + || type == JoinRelType.SEMI; } Review Comment: It's good to know there is already a discussion about this before in CALCITE-4623. Consider this case, we have a plan below: ```xml LogicalJoin(condition=[=($7, $9)], joinType=[inner]) LogicalTableScan(table=[[CATALOG, SALES, EMP]]) LogicalAggregate(group=[{0}], agg#0=[MIN($1)]) LogicalProject(DEPTNO=[$0], $f0=[true]) LogicalTableScan(table=[[CATALOG, SALES, DEPT]]) ``` After `JoinOnUniqueToSemiJoinRule`, it would be transformed to: ```xml LogicalJoin(condition=[=($7, $9)], joinType=[semi]) LogicalTableScan(table=[[CATALOG, SALES, EMP]]) LogicalAggregate(group=[{0}], agg#0=[MIN($1)]) LogicalProject(DEPTNO=[$0], $f0=[true]) LogicalTableScan(table=[[CATALOG, SALES, DEPT]]) ``` And we can still use `JoinToSemiJoinRule` to remove the `Aggregate`: ```xml LogicalJoin(condition=[=($7, $9)], joinType=[semi]) LogicalTableScan(table=[[CATALOG, SALES, EMP]]) LogicalProject(DEPTNO=[$0], $f0=[true]) LogicalTableScan(table=[[CATALOG, SALES, DEPT]]) ``` In many cases, we would not expect the rules firing orders, especially in `HepPlanner`, hence the above transforming order is valid and should be valid IMHO. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@calcite.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org