[GitHub] [calcite] hannerwang commented on a change in pull request #2408: [CALCITE-4512] Optimize when GROUP BY or HAVING alias should be substituted with select item

[GitBox]

hannerwang commented on a change in pull request #2408:
URL: https://github.com/apache/calcite/pull/2408#discussion_r623676488



##########
File path: 
core/src/test/resources/org/apache/calcite/test/SqlToRelConverterTest.xml
##########
@@ -142,14 +145,15 @@ LogicalAggregate(group=[{}], EXPR$0=[COUNT()])
     <TestCase name="testAliasInHaving">
         <Resource name="plan">
             <![CDATA[
-LogicalFilter(condition=[>($0, 1)])
-  LogicalAggregate(group=[{}], E=[COUNT()])
-    LogicalProject(EMPNO=[$0])
-      LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+LogicalProject(ENAME=[$0], E=[$1], D=[$1])
+  LogicalFilter(condition=[>($1, 2)])
+    LogicalAggregate(group=[{0}], E=[COUNT()])
+      LogicalProject(ENAME=[$1], EMPNO=[$0], DEPTNO=[$7])
+        LogicalTableScan(table=[[CATALOG, SALES, EMP]])
 ]]>

Review comment:
       it's the result of reducing COUNT aggregation whose args type has NOT 
NULL constraint to be count(&ast;). In this case, EMPNO and DEPTNO are integer 
and not null, so count(empno) and count(deptno) can be reduced as just one 
count(&ast;), furthermore the count(&ast;) > 1 and count(&ast;) > 2 can be 
reduced to count(&ast;) > 2.




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