[SPARK-29606][SQL] Improve EliminateOuterJoin performance

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/LogicalPlan.scala

@@ -176,10 +176,16 @@ abstract class UnaryNode extends LogicalPlan {
         allConstraints += EqualNullSafe(a.toAttribute, l)
       case a @ Alias(e, _) =>
         // For every alias in `projectList`, replace the reference in constraints by its attribute.
-        allConstraints ++= allConstraints.map(_ transform {
-          case expr: Expression if expr.semanticEquals(e) =>
-            a.toAttribute
-        })
+        allConstraints ++= allConstraints.map {
+          // To Avoid generating too many constraints, for example,
+          //   SELECT a AS a1, b AS b1, ab AS ab1 FROM (SELECT a, b, a + b AS ab FROM tbl) t
+          //   Avoid generating ((a#4 + b1#2) <=> ab#0) for ((a#4 + b#5) <=> ab#0).
+          case e @ EqualNullSafe(l, _: AttributeReference) if l.references.size > 1 => e
+          case other => other transform {
+            case expr: Expression if expr.semanticEquals(e) =>
+              a.toAttribute
+            }
+        }
         allConstraints += EqualNullSafe(e, a.toAttribute)
       case _ => // Don't change.
     }

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/plans/ConstraintPropagationSuite.scala

@@ -422,4 +422,12 @@ class ConstraintPropagationSuite extends SparkFunSuite with PlanTest {
       assert(aliasedRelation.analyze.constraints.isEmpty)
     }
   }
+
+  test("SPARK-29606 Avoid generating too many constraints") {
+    val aliasedRelation = LocalRelation('a.int, 'b.int, 'c.int)
+      .select('a, 'b, 'c, ('a + 'b + 'c).as("abc"))
+      .select('a.as("a1"), 'b.as("b1"), 'c.as("c1"), 'abc.as("abc1"))
+    assert(aliasedRelation.analyze.isInstanceOf[Project])
+    assert(aliasedRelation.analyze.asInstanceOf[Project].validConstraints.size === 5)
+  }
 }