AMashenkov commented on code in PR #1629:
URL: https://github.com/apache/ignite-3/pull/1629#discussion_r1114797387
##########
modules/sql-engine/src/main/java/org/apache/ignite/internal/sql/engine/exec/rel/SortNode.java:
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@@ -38,16 +43,45 @@
/** Rows buffer. */
private final PriorityQueue<RowT> rows;
+ /** SQL select limit. Negative if disabled. */
+ private final int limit;
+
+ /** Reverse-ordered rows in case of limited sort. */
+ private List<RowT> reversed;
+
/**
* Constructor.
*
- * @param ctx Execution context.
+ * @param ctx Execution context.
* @param comp Rows comparator.
+ * @param offset Offset.
+ * @param fetch Limit.
*/
- public SortNode(ExecutionContext<RowT> ctx, Comparator<RowT> comp) {
+ public SortNode(ExecutionContext<RowT> ctx,
+ Comparator<RowT> comp,
+ @Nullable Supplier<Integer> offset,
+ @Nullable Supplier<Integer> fetch) {
super(ctx);
+ assert fetch == null || fetch.get() >= 0;
+ assert offset == null || offset.get() >= 0;
- rows = comp == null ? new PriorityQueue<>() : new
PriorityQueue<>(comp);
+ limit = fetch == null ? -1 : fetch.get() + (offset == null ? 0 :
offset.get());
+
+ if (limit < 1) {
+ rows = new PriorityQueue<>(comp);
+ } else {
+ rows = new BoundedPriorityQueue<>(limit, comp == null ?
(Comparator<RowT>) Comparator.reverseOrder() : comp.reversed());
Review Comment:
Maybe we can use reverse order in both cases? or it will be less effective?
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