[CALCITE-3643] Prevent matching JoinCommuteRule when both inputs are …

…the same =($0, $1) and =($1, $1) are equivalent, however adding that permutation increases search space.
apache · Dec 29, 2019 · 8768a23 · 8768a23
1 parent 0341e97
commit 8768a23
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Showing 2 changed files with 9 additions and 7 deletions.
diff --git a/core/src/main/java/org/apache/calcite/rel/rules/JoinCommuteRule.java b/core/src/main/java/org/apache/calcite/rel/rules/JoinCommuteRule.java
@@ -38,6 +38,7 @@
 import com.google.common.collect.ImmutableList;
 
 import java.util.List;
+import java.util.function.Predicate;
 
 /**
  * Planner rule that permutes the inputs to a
@@ -67,7 +68,13 @@ public class JoinCommuteRule extends RelOptRule {
    */
   public JoinCommuteRule(Class<? extends Join> clazz,
       RelBuilderFactory relBuilderFactory, boolean swapOuter) {
-    super(operand(clazz, any()), relBuilderFactory, null);
+    // FIXME Enable this rule for joins with system fields
+    super(
+        operandJ(clazz, null,
+            (Predicate<Join>) j -> j.getLeft().getId() != j.getRight().getId()
+                && j.getSystemFieldList().isEmpty(),
+            any()),
+        relBuilderFactory, null);
     this.swapOuter = swapOuter;
   }
 
@@ -143,11 +150,6 @@ public static RelNode swap(Join join, boolean swapOuterJoins,
   public void onMatch(final RelOptRuleCall call) {
     Join join = call.rel(0);
 
-    if (!join.getSystemFieldList().isEmpty()) {
-      // FIXME Enable this rule for joins with system fields
-      return;
-    }
-
     final RelNode swapped = swap(join, this.swapOuter, call.builder());
     if (swapped == null) {
       return;

diff --git a/core/src/test/resources/sql/join.iq b/core/src/test/resources/sql/join.iq
@@ -198,7 +198,7 @@ EnumerableCalc(expr#0..1=[{inputs}], DEPTNO=[$t1], ENAME=[$t0])
     EnumerableHashJoin(condition=[=($2, $4)], joinType=[inner])
       EnumerableCalc(expr#0..7=[{inputs}], expr#8=[10], expr#9=[+($t7, $t8)], proj#0..1=[{exprs}], $f8=[$t9])
         EnumerableTableScan(table=[[scott, EMP]])
-      EnumerableCalc(expr#0..3=[{inputs}], expr#4=[+($t3, $t1)], expr#5=[CAST($t4):INTEGER], DEPTNO=[$t3], $f16=[$t5])
+      EnumerableCalc(expr#0..3=[{inputs}], expr#4=[+($t1, $t3)], expr#5=[CAST($t4):INTEGER], DEPTNO=[$t1], $f16=[$t5])
         EnumerableHashJoin(condition=[=($1, $3)], joinType=[inner])
           EnumerableCalc(expr#0..7=[{inputs}], EMPNO=[$t0], DEPTNO=[$t7])
             EnumerableTableScan(table=[[scott, EMP]])