[GitHub] [pinot] Jackie-Jiang commented on a diff in pull request #11444: Skip computation incase of Null Literal for case/when transformation

[via GitHub]

Jackie-Jiang commented on code in PR #11444:
URL: https://github.com/apache/pinot/pull/11444#discussion_r1306589151


##########
pinot-core/src/main/java/org/apache/pinot/core/operator/transform/function/CaseTransformFunction.java:
##########
@@ -128,16 +129,22 @@ private void 
constructStatementListLegacy(List<TransformFunction> arguments) {
     for (int i = numWhenStatements; i < numWhenStatements * 2; i++) {
       _thenStatements.add(arguments.get(i));
     }
-    if (arguments.size() % 2 != 0) {
+    if (arguments.size() % 2 != 0 && 
isNotNullLiteralTransformation(arguments.get(arguments.size() - 1))) {
       _elseStatement = arguments.get(arguments.size() - 1);
     }
   }
 
   private TransformResultMetadata calculateResultMetadata() {
-    TransformResultMetadata elseStatementResultMetadata = 
_elseStatement.getResultMetadata();
-    DataType dataType = elseStatementResultMetadata.getDataType();
-    Preconditions.checkState(elseStatementResultMetadata.isSingleValue(),
-        "Unsupported multi-value expression in the ELSE clause");
+    DataType dataType;

Review Comment:
   Good catch



##########
pinot-core/src/main/java/org/apache/pinot/core/operator/transform/function/CaseTransformFunction.java:
##########
@@ -128,16 +129,22 @@ private void 
constructStatementListLegacy(List<TransformFunction> arguments) {
     for (int i = numWhenStatements; i < numWhenStatements * 2; i++) {
       _thenStatements.add(arguments.get(i));
     }
-    if (arguments.size() % 2 != 0) {
+    if (arguments.size() % 2 != 0 && 
isNotNullLiteralTransformation(arguments.get(arguments.size() - 1))) {
       _elseStatement = arguments.get(arguments.size() - 1);
     }
   }
 
   private TransformResultMetadata calculateResultMetadata() {
-    TransformResultMetadata elseStatementResultMetadata = 
_elseStatement.getResultMetadata();
-    DataType dataType = elseStatementResultMetadata.getDataType();
-    Preconditions.checkState(elseStatementResultMetadata.isSingleValue(),
-        "Unsupported multi-value expression in the ELSE clause");
+    DataType dataType;
+    if (_elseStatement == null) {
+      // only possible in case of Null Literal transformation.

Review Comment:
   This comment is not accurate. I believe the existing code has a bug that can 
throw `NPE` when there is no else statement. Suggest just removing this comment



##########
pinot-core/src/main/java/org/apache/pinot/core/operator/transform/function/CaseTransformFunction.java:
##########
@@ -257,6 +264,14 @@ public TransformResultMetadata getResultMetadata() {
     return _resultMetadata;
   }
 
+  private boolean isNotNullLiteralTransformation(TransformFunction function) {
+    if (Objects.equals(function.getName(), 
LiteralTransformFunction.FUNCTION_NAME)) {

Review Comment:
   ```suggestion
       if (function instanceof LiteralTransformFunction) {
   ```



##########
pinot-core/src/main/java/org/apache/pinot/core/operator/transform/function/CaseTransformFunction.java:
##########
@@ -257,6 +264,14 @@ public TransformResultMetadata getResultMetadata() {
     return _resultMetadata;
   }
 
+  private boolean isNotNullLiteralTransformation(TransformFunction function) {
+    if (Objects.equals(function.getName(), 
LiteralTransformFunction.FUNCTION_NAME)) {
+      LiteralTransformFunction literalFUnction = (LiteralTransformFunction) 
function;

Review Comment:
   (typo)
   ```suggestion
         LiteralTransformFunction literalFunction = (LiteralTransformFunction) 
function;
   ```



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