[jira] [Created] (CALCITE-3621) JDBC adapter can't push down sort to DB

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

Lei Jiang created CALCITE-3621:
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             Summary: JDBC adapter can't push down sort to DB
                 Key: CALCITE-3621
                 URL: https://issues.apache.org/jira/browse/CALCITE-3621
             Project: Calcite
          Issue Type: Bug
          Components: jdbc-adapter
    Affects Versions: 1.21.0
            Reporter: Lei Jiang
            Assignee: Lei Jiang
             Fix For: 1.22.0


JDBC adapter can't push down sort to DB
{code:java}
select ename from scott.emp order by empno
{code}
{code:java}
PLAN=EnumerableSort(sort0=[$1], dir0=[ASC])
  JdbcToEnumerableConverter
    JdbcProject(ENAME=[$1], EMPNO=[$0])
      JdbcTableScan(table=[[SCOTT, EMP]])
{code}
 It should be:
{code:java}
PLAN=JdbcToEnumerableConverter
  JdbcSort(sort0=[$1], dir0=[ASC])
    JdbcProject(ENAME=[$1], EMPNO=[$0])
      JdbcTableScan(table=[[SCOTT, EMP]])
{code}
 I think the root cause is JdbcSortRule, it convert input's trait to "JDBC, {color:#FF0000}[1]{color}". that is, input's relset will add a "JDBC, [1]" subset. But there is nothing rule can convert that input to a rel with "JDBC, {color:#FF0000}[1]{color}", so EnumerableSort win.
{code:java}
public RelNode convert(Sort sort, boolean convertInputTraits) {
  final RelTraitSet traitSet = sort.getTraitSet().replace(out);

  final RelNode input;
  if (convertInputTraits) {
    input = convert(sort.getInput(), traitSet);
  } else {
    input = sort.getInput();
  }

  return new JdbcSort(sort.getCluster(), traitSet,
      input, sort.getCollation(), sort.offset, sort.fetch);
}
{code}
This is my a part of change. 
{code:java}
public RelNode convert(Sort sort, boolean convertInputTraits) {
  final RelTraitSet traitSet = sort.getTraitSet().replace(out);
  RelTraitSet inputTraitSet = traitSet.replace(RelCollations.EMPTY);

  final RelNode input;
  if (convertInputTraits) {
    input = convert(sort.getInput(), inputTraitSet);
  } else {
    input = sort.getInput();
  }

  return new JdbcSort(sort.getCluster(), traitSet,
      input, sort.getCollation(), sort.offset, sort.fetch);
}
{code}
I have updated some classes to reslove this issue



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