adelapena commented on code in PR #2673:
URL: https://github.com/apache/cassandra/pull/2673#discussion_r1360986023
##########
src/java/org/apache/cassandra/cql3/statements/SelectStatement.java:
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@@ -1080,19 +1139,26 @@ public void processPartition(RowIterator partition,
QueryOptions options, Result
private boolean needsPostQueryOrdering()
{
- // We need post-query ordering only for queries with IN on the
partition key and an ORDER BY.
- return restrictions.keyIsInRelation() &&
!parameters.orderings.isEmpty();
+ // We need post-query ordering only for queries with IN on the
partition key and an ORDER BY or index restriction reordering
+ return restrictions.keyIsInRelation() &&
!parameters.orderings.isEmpty() || needIndexOrdering();
+ }
+
+ private boolean needIndexOrdering()
+ {
+ return orderingComparator != null &&
orderingComparator.indexOrdering();
}
/**
* Orders results when multiple keys are selected (using IN)
*/
- private void orderResults(ResultSet cqlRows)
+ private void orderResults(ResultSet cqlRows, QueryOptions options)
{
if (cqlRows.size() == 0 || !needsPostQueryOrdering())
return;
- Collections.sort(cqlRows.rows, orderingComparator);
+ Comparator<List<ByteBuffer>> comparator =
orderingComparator.prepareFor(table, getRowFilter(options), options);
+ if (comparator != null)
+ Collections.sort(cqlRows.rows, comparator);
Review Comment:
Nit: this can be slightly simplified:
```suggestion
cqlRows.rows.sort(comparator);
```
Also, it might be worth adding a comment saying that this orders first by
the indexed column, then by primary key. This guarantee will probably be useful
if we support paging in the future.
The order is that way even when we only consider the indexed column when
sorting here. That's because the replica results have been returned ordered by
primary key. The stability of the used sorting algorithm (merge sort) ensures
that rows with the same value-based index score preserve the original primary
key order.
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