[jira] [Created] (CALCITE-4803) RelNode lost alias after remove Project operator

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

xzh_dz created CALCITE-4803:
-------------------------------

             Summary: RelNode lost alias after remove Project operator
                 Key: CALCITE-4803
                 URL: https://issues.apache.org/jira/browse/CALCITE-4803
             Project: Calcite
          Issue Type: Improvement
            Reporter: xzh_dz


 In my project, I often use `RelOptRule` to optimize relational algebra. In the process of materialized view optimization, after removing the `Project operator`, I found that RelNode lost its alias and their relational algebra is not equivalent.Examples can be reproduced as follows.
 
{code:java}
// code placeholder
org.apache.calcite.test.SqlToRelConverterTest
@Test void testLoseAlias() {
  final String sql = "select ename as e, deptno as d, count(distinct empno) from emp group by ename, deptno";
  final RelNode rel = tester.convertSqlToRel(sql).rel;
  // LogicalAggregate(group=[{0, 1}], EXPR$2=[COUNT(DISTINCT $2)])
  //  LogicalProject(E=[$1], D=[$7], EMPNO=[$0])
  //    LogicalTableScan(table=[[CATALOG, SALES, EMP]])
  System.out.println(RelOptUtil.toString(rel));
  final HepProgramBuilder programBuilder = HepProgram.builder();
  programBuilder.addRuleInstance(CoreRules.AGGREGATE_PROJECT_MERGE);
  final HepPlanner planner = new HepPlanner(programBuilder.build());
  planner.setRoot(rel);
  final RelNode relOpt = planner.findBestExp();
  //LogicalAggregate(group=[{1, 7}], EXPR$2=[COUNT(DISTINCT $0)])
  //  LogicalTableScan(table=[[CATALOG, SALES, EMP]])
  System.out.println(RelOptUtil.toString(relOpt));
  // [ENAME, DEPTNO, EXPR$2]
  System.out.println(relOpt.getRowType().getFieldNames());
}
{code}
 
 



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