KE-11534 keep ifnull operator rather than convert to case when

core/src/main/java/org/apache/calcite/sql2rel/StandardConvertletTable.java

@@ -119,7 +119,7 @@ private StandardConvertletTable() {
         SqlStdOperatorTable.IS_NOT_NULL);
     addAlias(SqlLibraryOperators.NULL_SAFE_EQUAL, SqlStdOperatorTable.IS_NOT_DISTINCT_FROM);
     addAlias(SqlStdOperatorTable.PERCENT_REMAINDER, SqlStdOperatorTable.MOD);
-    addAlias(SqlLibraryOperators.IFNULL, SqlLibraryOperators.NVL);
+    // addAlias(SqlLibraryOperators.IFNULL, SqlLibraryOperators.NVL); // kylin IFNULL ≠ NVL for cc
 
     // Register convertlets for specific objects.
     registerOp(SqlStdOperatorTable.CAST, this::convertCast);
@@ -166,6 +166,7 @@ private StandardConvertletTable() {
     registerOp(SqlLibraryOperators.DECODE,
         StandardConvertletTable::convertDecode);
     registerOp(SqlLibraryOperators.IF, StandardConvertletTable::convertIf);
+    registerOp(SqlLibraryOperators.IFNULL, StandardConvertletTable::convertIfNull);
 
     // Expand "x NOT LIKE y" into "NOT (x LIKE y)"
     registerOp(SqlStdOperatorTable.NOT_LIKE,
@@ -326,6 +327,20 @@ private static RexNode convertNvl(SqlRexContext cx, SqlCall call) {
         ));
   }
 
+  /** Converts a call to the IfNull function. */
+  private static RexNode convertIfNull(SqlRexContext cx, SqlCall call) {
+    final RexBuilder rexBuilder = cx.getRexBuilder();
+    final RexNode operand0 =
+        cx.convertExpression(call.getOperandList().get(0));
+    final RexNode operand1 =
+        cx.convertExpression(call.getOperandList().get(1));
+    final RelDataType type =
+        cx.getValidator().getValidatedNodeType(call);
+    // Preserve Operand Nullability
+    return rexBuilder.makeCall(type, SqlLibraryOperators.IFNULL,
+        ImmutableList.of(operand0, operand1));
+  }
+
   /** Converts a call to the DECODE function. */
   private static RexNode convertDecode(SqlRexContext cx, SqlCall call) {
     final RexBuilder rexBuilder = cx.getRexBuilder();

gradle.properties

@@ -27,7 +27,7 @@ systemProp.org.gradle.internal.publish.checksums.insecure=true
 # This is version for Calcite itself
 # Note: it should not include "-SNAPSHOT" as it is automatically added by build.gradle.kts
 # Release version can be generated by using -Prelease or -Prc=<int> arguments
-calcite.version=1.30.0-kylin-4.x-r04
+calcite.version=1.30.0-kylin-4.x-r05
 # This is a version to be used from Maven repository. It can be overridden by localAvatica below
 calcite.avatica.version=1.20.0