[CALCITE-4783] RelFieldTrimmer incorrectly drops filter condition

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.29.0
• Labels: pull-request-available
• Assignee: Unassigned
• Reporter: xzh_dz
• Created: 17/Sep/21 07:37
• Updated: 04/Jan/22 08:27
• Resolved: 04/Jan/22 08:27

Description

// code placeholder
org.apache.calcite.test.SqlToRelConverterTest
@Test void testTrim() {
  final String sql = "select count(*) from emp where ename = '1'";
  final RelNode rel = tester.convertSqlToRel(sql).rel;
  final HepProgramBuilder programBuilder = HepProgram.builder();
  programBuilder.addRuleInstance(CoreRules.FILTER_TO_CALC);
  final HepPlanner planner = new HepPlanner(programBuilder.build());
  planner.setRoot(rel);
  final RelNode calc = planner.findBestExp();
  final List<RelOptTable> relOptTables = RelOptUtil.findAllTables(calc);
  RelOptSchema relOptSchema = null;
  if (relOptTables.size() != 0) {
    relOptSchema = relOptTables.get(0).getRelOptSchema();
  }
  final RelBuilder relBuilder = RelFactories.LOGICAL_BUILDER.create(
      calc.getCluster(), relOptSchema);
  final RelFieldTrimmer fieldTrimmer = new RelFieldTrimmer(null, relBuilder);
  final RelNode trimmed = fieldTrimmer.trim(calc);
  System.out.println(RelOptUtil.toString(trimmed));
}
rel:
LogicalAggregate(group=[{}], EXPR$0=[COUNT()])
  LogicalProject($f0=[0])
    LogicalFilter(condition=[=($1, '1')])
      LogicalTableScan(table=[[CATALOG, SALES, EMP]])

trimmed:
LogicalAggregate(group=[{}], EXPR$0=[COUNT()])
  LogicalTableScan(table=[[CATALOG, SALES, EMP]])

 In this case,RelFieldTrimmer incorrectly drops filter condition.`RelNode(trimmed)` is incorrect,there is no predicate condition `ename = '1'` in final `RelNode(trimmed)`.During Calc operator trim, predicates should not be lost. 

Issue Links

• links to: GitHub Pull Request #2605