gianm commented on code in PR #19726:
URL: https://github.com/apache/druid/pull/19726#discussion_r3636416189
##########
processing/src/main/java/org/apache/druid/segment/QueryableIndexCursorFactory.java:
##########
@@ -200,15 +201,49 @@ private CursorHolder makeSingleGroupClusteredCursorHolder(
);
}
+ // A single cluster group is physically sorted by its group ordering (the
segment ordering with the constant
+ // clustering prefix dropped). When the query wants __time ordering and
__time is the first non-clustering column,
+ // advertise that __time-first group ordering so the holder reports (and
honors, incl. descending) time ordering --
+ // matching the multi-group merge path, so the same query does not depend
on how many groups survive pruning.
+ // Otherwise advertise the full clustering-first segment ordering. Note
the clustering prefix is constant across
+ // this single group, so both orderings are truthful descriptions of the
exposed rows.
+ final ClusteredValueGroupsBaseTableSchema summary =
valueGroup.getSummary();
+ final List<OrderBy> ordering =
+ isGroupTimeOrderingRequested(spec, summary) ?
summary.getGroupOrdering() : summary.getOrdering();
+
// groupIndex exposes the group's clustering columns as constant columns,
no selector wrapper is needed
return new QueryableIndexCursorHolder(
groupIndex,
plan.rebuildCursorBuildSpec(spec, valueGroup),
QueryableIndexTimeBoundaryInspector.create(groupIndex),
- valueGroup.getSummary().getOrdering()
+ ordering
);
}
+ /**
Review Comment:
IMO this javadoc is too long. Try:
```
// Whether the query requested {@code __time} ordering and each cluster
group is individually
// time-ordered. In this case, we return time ordered cursors.
```
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