[SPARK-19766][SQL] Constant alias columns in INNER JOIN should not be folded by FoldablePropagation rule

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala

@@ -457,7 +457,7 @@ object FoldablePropagation extends Rule[LogicalPlan] {
         // join is not always picked from its children, but can also be null.
         // TODO(cloud-fan): It seems more reasonable to use new attributes as the output attributes
         // of outer join.
-        case j @ Join(_, _, Inner, _) =>
+        case j @ Join(_, _, Inner, _) if !stop =>
           j.transformExpressions(replaceFoldable)
 
         // We can fold the projections an expand holds. However expand changes the output columns

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/FoldablePropagationSuite.scala

@@ -130,6 +130,20 @@ class FoldablePropagationSuite extends PlanTest {
     comparePlans(optimized, correctAnswer)
   }
 
+  test("Propagate in inner join") {
+    val ta = testRelation.select('a, Literal(1).as('tag))
+      .union(testRelation.select('a, Literal(2).as('tag)))
+      .subquery('ta)
+    val tb = testRelation.select('a, Literal(1).as('tag))
+      .union(testRelation.select('a, Literal(2).as('tag)))
+      .subquery('tb)
+    val query = ta.join(tb, Inner,
+      Some("ta.a".attr === "tb.a".attr && "ta.tag".attr === "tb.tag".attr))
+    val optimized = Optimize.execute(query.analyze)
+    val correctAnswer = query.analyze
+    comparePlans(optimized, correctAnswer)
+  }
+
   test("Propagate in expand") {
     val c1 = Literal(1).as('a)
     val c2 = Literal(2).as('b)

sql/core/src/test/resources/sql-tests/inputs/inner-join.sql

@@ -0,0 +1,17 @@
+CREATE TEMPORARY VIEW t1 AS SELECT * FROM VALUES (1) AS GROUPING(a);
+CREATE TEMPORARY VIEW t2 AS SELECT * FROM VALUES (1) AS GROUPING(a);
+CREATE TEMPORARY VIEW t3 AS SELECT * FROM VALUES (1), (1) AS GROUPING(a);
+CREATE TEMPORARY VIEW t4 AS SELECT * FROM VALUES (1), (1) AS GROUPING(a);
+
+CREATE TEMPORARY VIEW ta AS
+SELECT a, 'a' AS tag FROM t1
+UNION ALL
+SELECT a, 'b' AS tag FROM t2;
+
+CREATE TEMPORARY VIEW tb AS
+SELECT a, 'a' AS tag FROM t3
+UNION ALL
+SELECT a, 'b' AS tag FROM t4;
+
+-- SPARK-19766 Constant alias columns in INNER JOIN should not be folded by FoldablePropagation rule
+SELECT tb.* FROM ta INNER JOIN tb ON ta.a = tb.a AND ta.tag = tb.tag;

sql/core/src/test/resources/sql-tests/results/inner-join.sql.out

@@ -0,0 +1,68 @@
+-- Automatically generated by SQLQueryTestSuite
+-- Number of queries: 13
+
+
+-- !query 0
+CREATE TEMPORARY VIEW t1 AS SELECT * FROM VALUES (1) AS GROUPING(a)
+-- !query 0 schema
+struct<>
+-- !query 0 output
+
+
+
+-- !query 1
+CREATE TEMPORARY VIEW t2 AS SELECT * FROM VALUES (1) AS GROUPING(a)
+-- !query 1 schema
+struct<>
+-- !query 1 output
+
+
+
+-- !query 2
+CREATE TEMPORARY VIEW t3 AS SELECT * FROM VALUES (1), (1) AS GROUPING(a)
+-- !query 2 schema
+struct<>
+-- !query 2 output
+
+
+
+-- !query 3
+CREATE TEMPORARY VIEW t4 AS SELECT * FROM VALUES (1), (1) AS GROUPING(a)
+-- !query 3 schema
+struct<>
+-- !query 3 output
+
+
+
+-- !query 4
+CREATE TEMPORARY VIEW ta AS
+SELECT a, 'a' AS tag FROM t1
+UNION ALL
+SELECT a, 'b' AS tag FROM t2
+-- !query 4 schema
+struct<>
+-- !query 4 output
+
+
+
+-- !query 5
+CREATE TEMPORARY VIEW tb AS
+SELECT a, 'a' AS tag FROM t3
+UNION ALL
+SELECT a, 'b' AS tag FROM t4
+-- !query 5 schema
+struct<>
+-- !query 5 output
+
+
+
+-- !query 6
+SELECT tb.* FROM ta INNER JOIN tb ON ta.a = tb.a AND ta.tag = tb.tag
+-- !query 6 schema
+struct<a:int,tag:string>
+-- !query 6 output
+1	a
+1	a
+1	b
+1	b
+