JiajunBernoulli commented on code in PR #2997:
URL: https://github.com/apache/calcite/pull/2997#discussion_r1052093557
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core/src/main/java/org/apache/calcite/rel/rel2sql/RelToSqlConverter.java:
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@@ -868,19 +867,35 @@ public Result visit(Sort e) {
if (hasTrickyRollup(e, aggregate)) {
// MySQL 5 does not support standard "GROUP BY ROLLUP(x, y)", only
// the non-standard "GROUP BY x, y WITH ROLLUP".
- // It does not allow "WITH ROLLUP" in combination with "ORDER BY",
- // but "GROUP BY x, y WITH ROLLUP" implicitly sorts by x, y,
+ List<Integer> rollupList =
Aggregate.Group.getRollup(aggregate.getGroupSets());
+ List<Integer> sortList = e.getCollation()
+ .getFieldCollations()
+ .stream()
+ .map(f -> aggregate.getGroupSet().nth(f.getFieldIndex()))
+ .collect(Collectors.toList());
+ // "GROUP BY x, y WITH ROLLUP" implicitly sorts by x, y,
// so skip the ORDER BY.
- final Set<Integer> groupList = new LinkedHashSet<>();
- for (RelFieldCollation fc : e.collation.getFieldCollations()) {
- groupList.add(aggregate.getGroupSet().nth(fc.getFieldIndex()));
- }
- groupList.addAll(Aggregate.Group.getRollup(aggregate.getGroupSets()));
+ boolean isImplicitlySort = rollupList.subList(0,
sortList.size()).equals(sortList);
Review Comment:
I didn't have this consciousness before, thank you for letting me learn.
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