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https://issues.apache.org/jira/browse/CALCITE-3621?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Danny Chen resolved CALCITE-3621.
---------------------------------
Resolution: Fixed
Fixed in
[fe0a2fe|https://github.com/apache/calcite/commit/fe0a2fe7dde4a4a342cfc50f2f9da983cc60c479],
thanks for your PR, [~Lei Jiang] !
> 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
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.22.0
>
> Time Spent: 4h 50m
> Remaining Estimate: 0h
>
> 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: convert input's trait to "JDBC, []"
> {code:java}
> public RelNode convert(Sort sort, boolean convertInputTraits) {
> final RelTraitSet traitSet = sort.getTraitSet().replace(out);
> //update again
> final RelTraitSet inputTraitSet =
> sort.getInput().getTraitSet().replace(out);
> final RelNode input;
> if (convertInputTraits) {
> //update
> input = convert(sort.getInput(), inputTraitSet);
> } else {
> input = sort.getInput();
> }
> return new JdbcSort(sort.getCluster(), traitSet,
> input, sort.getCollation(), sort.offset, sort.fetch);
> }
> {code}
>
> By the way, when we switch "_calcite.enable.enumerable_" to "_false_" without
> this change, this case will be failed.
> {code:java}
> java.sql.SQLException: Error while executing SQL "explain plan for select
> ename
> from scott.emp
> order by empno": There are not enough rules to produce a node with desired
> properties: convention=ENUMERABLE, sort=[1].
> Missing conversion is JdbcTableScan[sort: [] -> [0]]
> There is 1 empty subset: rel#34:Subset#0.JDBC.SCOTT.[0], the relevant part of
> the original plan is as follows
> 0:JdbcTableScan(table=[[SCOTT, EMP]])
> {code}
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