[jira] [Created] (CALCITE-4037) AggregateProjectMergeRule doesn't always respect column aliases

["Sylvain Crozon (Jira)" <ji...@apache.org>]

Sylvain Crozon created CALCITE-4037:
---------------------------------------

             Summary: AggregateProjectMergeRule doesn't always respect column aliases
                 Key: CALCITE-4037
                 URL: https://issues.apache.org/jira/browse/CALCITE-4037
             Project: Calcite
          Issue Type: Bug
          Components: core
            Reporter: Sylvain Crozon
         Attachments: fix-AggregateProjectMergeRule.patch

When columns aggregated over are given an alias, but not aggregated values, the alias is lost: 

{{select deptno as x, sum(sal)}}
 {{from emp}}
 {{group by deptno}}

has the following plan

{{LogicalAggregate(group=[\\{0}], EXPR$1=[SUM($1)])}}
 {{  LogicalProject(X=[$7], SAL=[$5])}}
 {{    LogicalTableScan(table=[[CATALOG, SALES, EMP]])}}

 which becomes  

{{LogicalAggregate(group=[\\{7}], EXPR$1=[SUM($5)])}}
 {{  LogicalTableScan(table=[[CATALOG, SALES, EMP]])}}

after the AggregateProjectMergeRule

 

I attempted a fix by comparing the row type's field names of the project node with its input, and skip merging with the agg node if they don't match. That works for the use case above, however that breaks quite a few unit tests. Some of them, I believe, should be updated like 

testAggregateMerge1, the alias in the SQL queries are lost in the final plan. But for other use cases, mostly when there's a join, the simple column name comparison is not enough. 

 

 



--
This message was sent by Atlassian Jira
(v8.3.4#803005)