[CALCITE-5483] ProjectAggregateMergeRule throws exception if literal is non-numeric

core/src/main/java/org/apache/calcite/rel/rules/ProjectAggregateMergeRule.java

@@ -104,20 +104,21 @@ && kindCount(project.getProjects(), SqlKind.CASE) == 0) {
             final RexInputRef ref0 = (RexInputRef) isNotNull.operands.get(0);
             final RexCall cast = (RexCall) operands.get(1);
             final RexInputRef ref1 = (RexInputRef) cast.operands.get(0);
+            if (ref0.getIndex() != ref1.getIndex()) {
+              break;
+            }
+            final int aggCallIndex = ref1.getIndex() - aggregate.getGroupCount();
+            if (aggCallIndex < 0) {
+              break;
+            }
+            final AggregateCall aggCall = aggregate.getAggCallList().get(aggCallIndex);
+            if (aggCall.getAggregation().getKind() != SqlKind.SUM) {
+              break;
+            }
             final RexLiteral literal = (RexLiteral) operands.get(2);
-            if (ref0.getIndex() == ref1.getIndex()
-                && Objects.equals(literal.getValueAs(BigDecimal.class), BigDecimal.ZERO)) {
-              final int aggCallIndex =
-                  ref1.getIndex() - aggregate.getGroupCount();
-              if (aggCallIndex >= 0) {
-                final AggregateCall aggCall =
-                    aggregate.getAggCallList().get(aggCallIndex);
-                if (aggCall.getAggregation().getKind() == SqlKind.SUM) {
-                  int j =
-                      findSum0(cluster.getTypeFactory(), aggCall, aggCallList);
-                  return cluster.getRexBuilder().makeInputRef(call.type, j);
-                }
-              }
+            if (Objects.equals(literal.getValueAs(BigDecimal.class), BigDecimal.ZERO)) {
+              int j = findSum0(cluster.getTypeFactory(), aggCall, aggCallList);
+              return cluster.getRexBuilder().makeInputRef(call.type, j);
             }
           }
           break;

core/src/test/java/org/apache/calcite/test/RelOptRulesTest.java

@@ -106,6 +106,7 @@
 import org.apache.calcite.sql.SqlOperator;
 import org.apache.calcite.sql.fun.SqlLibrary;
 import org.apache.calcite.sql.fun.SqlStdOperatorTable;
+import org.apache.calcite.sql.test.SqlTestFactory;
 import org.apache.calcite.sql.type.OperandTypes;
 import org.apache.calcite.sql.type.ReturnTypes;
 import org.apache.calcite.sql.type.SqlTypeName;
@@ -5241,6 +5242,47 @@ private HepProgram getTransitiveProgram() {
         .check();
   }
 
+  /** Tests that ProjectAggregateMergeRule does nothing with non-numeric literals
+   * and does not throw an exception. */
+  @Test void testProjectAggregateMergeNonNumericLiteral() {
+    // Requires a NULLABLE column to trigger
+    final SqlTestFactory.CatalogReaderFactory catalogReaderFactory = (typeFactory, caseSensitive) ->
+        new MockCatalogReader(typeFactory, caseSensitive) {
+          @Override public MockCatalogReader init() {
+            MockSchema schema = new MockSchema("SALES");
+            registerSchema(schema);
+            final boolean nullable = true;
+            final RelDataType timestampType = typeFactory.createTypeWithNullability(
+                typeFactory.createSqlType(SqlTypeName.TIMESTAMP),
+                nullable);
+            String tableName = "NULLABLE";
+            MockTable table = MockTable
+                .create(this, schema, tableName, false, 100);
+            table.addColumn("HIREDATE", timestampType);
+            registerTable(table);
+            return this;
+          }
+        }.init();
+    final String sql = "select hiredate, coalesce(hiredate, {ts '1969-12-31 00:00:00'}) as c1\n"
+        + "from sales.nullable\n"
+        + "group by hiredate";
+    sql(sql)
+        .withCatalogReaderFactory(catalogReaderFactory)
+        .withRule(CoreRules.PROJECT_AGGREGATE_MERGE)
+        .checkUnchanged();
+  }
+
+  @Test void testProjectAggregateMergeNoOpForNonSum() {
+    final String sql = "select coalesce(m, 0)\n"
+        + "from (\n"
+        + "  select max(deptno) as m\n"
+        + "  from sales.emp\n"
+        + ")";
+    sql(sql)
+        .withRule(CoreRules.PROJECT_AGGREGATE_MERGE)
+        .checkUnchanged();
+  }
+
   /**
    * Test case for AggregateMergeRule, should merge 2 aggregates
    * into a single aggregate.

core/src/test/resources/org/apache/calcite/test/RelOptRulesTest.xml

@@ -6329,6 +6329,37 @@ LogicalProject(EXPR$0=[+(+($1, $3), $2)])
   LogicalAggregate(group=[{0, 1}], MS=[MIN($2)], SS=[SUM($2)])
     LogicalProject(JOB=[$2], DEPTNO=[$7], SAL=[$5])
       LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+]]>
+    </Resource>
+  </TestCase>
+  <TestCase name="testProjectAggregateMergeNoOpForNonSum">
+    <Resource name="sql">
+      <![CDATA[select coalesce(m, 0)
+from (
+  select max(deptno) as m
+  from sales.emp
+)]]>
+    </Resource>
+    <Resource name="planBefore">
+      <![CDATA[
+LogicalProject(EXPR$0=[CASE(IS NOT NULL($0), CAST($0):INTEGER NOT NULL, 0)])
+  LogicalAggregate(group=[{}], M=[MAX($0)])
+    LogicalProject(DEPTNO=[$7])
+      LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+]]>
+    </Resource>
+  </TestCase>
+  <TestCase name="testProjectAggregateMergeNonNumericLiteral">
+    <Resource name="sql">
+      <![CDATA[select hiredate, coalesce(hiredate, {ts '1969-12-31 00:00:00'}) as c1
+from sales.nullable
+group by hiredate]]>
+    </Resource>
+    <Resource name="planBefore">
+      <![CDATA[
+LogicalProject(HIREDATE=[$0], C1=[CASE(IS NOT NULL($0), CAST($0):TIMESTAMP(0) NOT NULL, 1969-12-31 00:00:00)])
+  LogicalAggregate(group=[{0}])
+    LogicalTableScan(table=[[CATALOG, SALES, NULLABLE]])
 ]]>
     </Resource>
   </TestCase>