From ad883e143ff5e07ef961cf3f177876dc59290528 Mon Sep 17 00:00:00 2001
From: nobigo <nobigogle@gmail.com>
Date: Wed, 28 Aug 2024 09:12:27 +0800
Subject: [PATCH] [CALCITE-6548] Return type of COVAR_SAMP, COVAR_POP and
 VAR_SAMP should be nullable

---
 .../java/org/apache/calcite/sql/type/ReturnTypes.java     | 7 +++++--
 .../resources/org/apache/calcite/test/RelOptRulesTest.xml | 4 ++--
 .../java/org/apache/calcite/test/SqlOperatorTest.java     | 8 ++++----
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/core/src/main/java/org/apache/calcite/sql/type/ReturnTypes.java b/core/src/main/java/org/apache/calcite/sql/type/ReturnTypes.java
index bab91ec22c5..68778256c05 100644
--- a/core/src/main/java/org/apache/calcite/sql/type/ReturnTypes.java
+++ b/core/src/main/java/org/apache/calcite/sql/type/ReturnTypes.java
@@ -1402,7 +1402,8 @@ private static RelDataType multivalentStringWithSepSumPrecision(
         typeFactory.getTypeSystem().deriveAvgAggType(typeFactory,
             opBinding.getOperandType(0));
     if (opBinding.getGroupCount() == 0 || opBinding.hasFilter()
-        || opBinding.getOperator().kind == SqlKind.STDDEV_SAMP) {
+        || opBinding.getOperator().getKind() == SqlKind.STDDEV_SAMP
+        || opBinding.getOperator().getKind() == SqlKind.VAR_SAMP) {
       return typeFactory.createTypeWithNullability(relDataType, true);
     } else {
       return relDataType;
@@ -1414,7 +1415,9 @@ private static RelDataType multivalentStringWithSepSumPrecision(
     final RelDataType relDataType =
         typeFactory.getTypeSystem().deriveCovarType(typeFactory,
             opBinding.getOperandType(0), opBinding.getOperandType(1));
-    if (opBinding.getGroupCount() == 0 || opBinding.hasFilter()) {
+    if (opBinding.getGroupCount() == 0 || opBinding.hasFilter()
+        || opBinding.getOperator().kind == SqlKind.COVAR_POP
+        || opBinding.getOperator().kind == SqlKind.COVAR_SAMP) {
       return typeFactory.createTypeWithNullability(relDataType, true);
     } else {
       return relDataType;
diff --git a/core/src/test/resources/org/apache/calcite/test/RelOptRulesTest.xml b/core/src/test/resources/org/apache/calcite/test/RelOptRulesTest.xml
index bf3276d22cb..0963020e2c3 100644
--- a/core/src/test/resources/org/apache/calcite/test/RelOptRulesTest.xml
+++ b/core/src/test/resources/org/apache/calcite/test/RelOptRulesTest.xml
@@ -1521,7 +1521,7 @@ LogicalAggregate(group=[{0}], EXPR$1=[STDDEV_POP($1)], EXPR$2=[AVG($1)], EXPR$3=
     </Resource>
     <Resource name="planAfter">
       <![CDATA[
-LogicalProject(NAME=[$0], EXPR$1=[CAST(POWER(/(-($1, /(*($2, $2), $3)), $3), 0.5:DECIMAL(2, 1))):INTEGER NOT NULL], EXPR$2=[CAST(/($2, $3)):INTEGER NOT NULL], EXPR$3=[CAST(POWER(/(-($1, /(*($2, $2), $3)), CASE(=($3, 1), null:BIGINT, -($3, 1))), 0.5:DECIMAL(2, 1))):INTEGER], EXPR$4=[CAST(/(-($1, /(*($2, $2), $3)), $3)):INTEGER NOT NULL], EXPR$5=[CAST(/(-($1, /(*($2, $2), $3)), CASE(=($3, 1), null:BIGINT, -($3, 1)))):INTEGER NOT NULL])
+LogicalProject(NAME=[$0], EXPR$1=[CAST(POWER(/(-($1, /(*($2, $2), $3)), $3), 0.5:DECIMAL(2, 1))):INTEGER NOT NULL], EXPR$2=[CAST(/($2, $3)):INTEGER NOT NULL], EXPR$3=[CAST(POWER(/(-($1, /(*($2, $2), $3)), CASE(=($3, 1), null:BIGINT, -($3, 1))), 0.5:DECIMAL(2, 1))):INTEGER], EXPR$4=[CAST(/(-($1, /(*($2, $2), $3)), $3)):INTEGER NOT NULL], EXPR$5=[CAST(/(-($1, /(*($2, $2), $3)), CASE(=($3, 1), null:BIGINT, -($3, 1)))):INTEGER])
   LogicalAggregate(group=[{0}], agg#0=[$SUM0($2)], agg#1=[$SUM0($1)], agg#2=[COUNT()])
     LogicalProject(NAME=[$0], DEPTNO=[$1], $f2=[*($1, $1)])
       LogicalProject(NAME=[$1], DEPTNO=[$0])
@@ -12133,7 +12133,7 @@ LogicalAggregate(group=[{0}], EXPR$1=[STDDEV_POP($1)], EXPR$2=[AVG($1)], EXPR$3=
     </Resource>
     <Resource name="planAfter">
       <![CDATA[
-LogicalProject(NAME=[$0], EXPR$1=[CAST(POWER(/(-($1, /(*($2, $2), $3)), $3), 0.5:DECIMAL(2, 1))):INTEGER NOT NULL], EXPR$2=[CAST(/($2, $3)):INTEGER NOT NULL], EXPR$3=[CAST(POWER(/(-($1, /(*($2, $2), $3)), CASE(=($3, 1), null:BIGINT, -($3, 1))), 0.5:DECIMAL(2, 1))):INTEGER], EXPR$4=[CAST(/(-($1, /(*($2, $2), $3)), $3)):INTEGER NOT NULL], EXPR$5=[CAST(/(-($1, /(*($2, $2), $3)), CASE(=($3, 1), null:BIGINT, -($3, 1)))):INTEGER NOT NULL])
+LogicalProject(NAME=[$0], EXPR$1=[CAST(POWER(/(-($1, /(*($2, $2), $3)), $3), 0.5:DECIMAL(2, 1))):INTEGER NOT NULL], EXPR$2=[CAST(/($2, $3)):INTEGER NOT NULL], EXPR$3=[CAST(POWER(/(-($1, /(*($2, $2), $3)), CASE(=($3, 1), null:BIGINT, -($3, 1))), 0.5:DECIMAL(2, 1))):INTEGER], EXPR$4=[CAST(/(-($1, /(*($2, $2), $3)), $3)):INTEGER NOT NULL], EXPR$5=[CAST(/(-($1, /(*($2, $2), $3)), CASE(=($3, 1), null:BIGINT, -($3, 1)))):INTEGER])
   LogicalAggregate(group=[{0}], agg#0=[$SUM0($2)], agg#1=[$SUM0($1)], agg#2=[COUNT()])
     LogicalProject(NAME=[$0], DEPTNO=[$1], $f2=[*($1, $1)])
       LogicalProject(NAME=[$1], DEPTNO=[$0])
diff --git a/testkit/src/main/java/org/apache/calcite/test/SqlOperatorTest.java b/testkit/src/main/java/org/apache/calcite/test/SqlOperatorTest.java
index 5ca6f9b1569..b8898e42d90 100644
--- a/testkit/src/main/java/org/apache/calcite/test/SqlOperatorTest.java
+++ b/testkit/src/main/java/org/apache/calcite/test/SqlOperatorTest.java
@@ -14774,7 +14774,7 @@ void testTimestampDiff(boolean coercionEnabled) {
         "DECIMAL(19, 9)");
     f.checkType("covar_pop(CAST(NULL AS INTEGER),CAST(NULL AS INTEGER))",
         "INTEGER");
-    f.checkAggType("covar_pop(1.5, 2.5)", "DECIMAL(2, 1) NOT NULL");
+    f.checkAggType("covar_pop(1.5, 2.5)", "DECIMAL(2, 1)");
     if (!f.brokenTestsEnabled()) {
       return;
     }
@@ -14798,7 +14798,7 @@ void testTimestampDiff(boolean coercionEnabled) {
         "DECIMAL(19, 9)");
     f.checkType("covar_samp(CAST(NULL AS INTEGER),CAST(NULL AS INTEGER))",
         "INTEGER");
-    f.checkAggType("covar_samp(1.5, 2.5)", "DECIMAL(2, 1) NOT NULL");
+    f.checkAggType("covar_samp(1.5, 2.5)", "DECIMAL(2, 1)");
     if (!f.brokenTestsEnabled()) {
       return;
     }
@@ -14976,7 +14976,7 @@ void testTimestampDiff(boolean coercionEnabled) {
             false);
     f.checkType("var_samp(cast(null as varchar(2)))", "DECIMAL(19, 9)");
     f.checkType("var_samp(CAST(NULL AS INTEGER))", "INTEGER");
-    f.checkAggType("var_samp(DISTINCT 1.5)", "DECIMAL(2, 1) NOT NULL");
+    f.checkAggType("var_samp(DISTINCT 1.5)", "DECIMAL(2, 1)");
     final String[] values = {"0", "CAST(null AS FLOAT)", "3", "3"};
     if (!f.brokenTestsEnabled()) {
       return;
@@ -15004,7 +15004,7 @@ void testTimestampDiff(boolean coercionEnabled) {
             false);
     f.checkType("variance(cast(null as varchar(2)))", "DECIMAL(19, 9)");
     f.checkType("variance(CAST(NULL AS INTEGER))", "INTEGER");
-    f.checkAggType("variance(DISTINCT 1.5)", "DECIMAL(2, 1) NOT NULL");
+    f.checkAggType("variance(DISTINCT 1.5)", "DECIMAL(2, 1)");
     final String[] values = {"0", "CAST(null AS FLOAT)", "3", "3"};
     if (!f.brokenTestsEnabled()) {
       return;