[GitHub] [pinot] amrishlal commented on a change in pull request #7678: Fixing DISTINCT with AS function

[GitBox <gi...@apache.org>]

amrishlal commented on a change in pull request #7678:
URL: https://github.com/apache/pinot/pull/7678#discussion_r742387904



##########
File path: pinot-core/src/main/java/org/apache/pinot/core/operator/transform/function/TransformFunctionFactory.java
##########
@@ -82,6 +82,7 @@ private TransformFunctionFactory() {
           put(canonicalize(TransformFunctionType.LN.getName().toLowerCase()), LnTransformFunction.class);
           put(canonicalize(TransformFunctionType.SQRT.getName().toLowerCase()), SqrtTransformFunction.class);
 
+          put(canonicalize(TransformFunctionType.AS.getName().toLowerCase()), AsTransformFunction.class);

Review comment:
       Can we set it up so that user won't be able to invoke AS function directly from SQL, so that they use the AS keyword?

##########
File path: pinot-common/src/main/java/org/apache/pinot/sql/parsers/CalciteSqlParser.java
##########
@@ -161,7 +162,9 @@ private static void validateDistinctQuery(PinotQuery pinotQuery)
         }
         List<Expression> orderByList = pinotQuery.getOrderByList();
         if (orderByList != null) {
-          List<Expression> distinctExpressions = function.getOperands();
+          List<Expression> distinctExpressions = function.getOperands().stream().map(

Review comment:
       I thought Pinot coding convention didn't allow using "stream()" due to performance concerns?

##########
File path: pinot-common/src/test/java/org/apache/pinot/sql/parsers/rewriter/NonAggregationGroupByToDistinctQueryRewriterTest.java
##########
@@ -0,0 +1,86 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.pinot.sql.parsers.rewriter;
+
+import org.apache.pinot.common.request.PinotQuery;
+import org.apache.pinot.sql.parsers.CalciteSqlParser;
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+
+public class NonAggregationGroupByToDistinctQueryRewriterTest {
+
+  private static final QueryRewriter QUERY_REWRITER = new NonAggregationGroupByToDistinctQueryRewriter();
+
+  @Test
+  public void testQuery1() {
+    final PinotQuery pinotQuery = CalciteSqlParser.compileToPinotQuery("SELECT A FROM myTable GROUP BY A");
+    QUERY_REWRITER.rewrite(pinotQuery);
+    Assert.assertEquals(pinotQuery.getSelectList().get(0).getFunctionCall().getOperator(), "DISTINCT");
+    Assert.assertEquals(
+        pinotQuery.getSelectList().get(0).getFunctionCall().getOperands().get(0).getIdentifier().getName(), "A");
+  }
+
+  @Test
+  // SELECT col1+col2*5 FROM foo GROUP BY col1, col2 => SELECT distinct col1+col2*5 FROM foo
+  public void testQuery2() {
+    final PinotQuery pinotQuery =
+        CalciteSqlParser.compileToPinotQuery("SELECT col1+col2*5 FROM foo GROUP BY col1, col2");
+    QUERY_REWRITER.rewrite(pinotQuery);
+    Assert.assertEquals(pinotQuery.getSelectList().get(0).getFunctionCall().getOperator(), "DISTINCT");
+    Assert.assertEquals(
+        pinotQuery.getSelectList().get(0).getFunctionCall().getOperands().get(0).getFunctionCall().getOperands().get(0)
+            .getIdentifier().getName(), "col1");
+    Assert.assertEquals(
+        pinotQuery.getSelectList().get(0).getFunctionCall().getOperands().get(0).getFunctionCall().getOperands().get(1)
+            .getFunctionCall().getOperands().get(0).getIdentifier().getName(), "col2");
+    Assert.assertEquals(
+        pinotQuery.getSelectList().get(0).getFunctionCall().getOperands().get(0).getFunctionCall().getOperands().get(1)
+            .getFunctionCall().getOperands().get(1).getLiteral().getLongValue(), 5L);
+  }
+
+  @Test
+  // SELECT col1, col2 FROM foo GROUP BY col1, col2 => SELECT distinct col1, col2 FROM foo
+  public void testQuery3() {
+    final PinotQuery pinotQuery =
+        CalciteSqlParser.compileToPinotQuery("SELECT col1, col2 FROM foo GROUP BY col1, col2 ");
+    QUERY_REWRITER.rewrite(pinotQuery);
+    Assert.assertEquals(pinotQuery.getSelectList().get(0).getFunctionCall().getOperator(), "DISTINCT");
+    Assert.assertEquals(
+        pinotQuery.getSelectList().get(0).getFunctionCall().getOperands().get(0).getIdentifier().getName(), "col1");
+    Assert.assertEquals(
+        pinotQuery.getSelectList().get(0).getFunctionCall().getOperands().get(1).getIdentifier().getName(), "col2");
+  }
+
+  @Test
+  // SELECT col1 as col2 FROM foo GROUP BY col1 => SELECT distinct col1 as col2 FROM foo

Review comment:
       Can we have a test case with multiple expressions and column aliases? Something like: `SELECT DISTINCT col1 as a, col2 as b, concat(col3, col4, '') as c FROM foo`?




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