[GitHub] [doris] Gabriel39 commented on a diff in pull request #15663: [Improvement](topn) order by key topn query optimization

[GitBox <gi...@apache.org>]

Gabriel39 commented on code in PR #15663:
URL: https://github.com/apache/doris/pull/15663#discussion_r1071696041


##########
be/src/vec/olap/vcollect_iterator.h:
##########
@@ -72,6 +72,26 @@ class VCollectIterator {
     }
 
 private:
+    // next for topn query
+    Status topn_next(Block* block);

Review Comment:
   _topn_next



##########
be/src/vec/olap/vcollect_iterator.h:
##########
@@ -72,6 +72,26 @@ class VCollectIterator {
     }
 
 private:
+    // next for topn query
+    Status topn_next(Block* block);
+
+    class BlockRowposComparator {

Review Comment:
   BlockRowPosComparator



##########
be/src/vec/olap/vcollect_iterator.cpp:
##########
@@ -185,13 +195,170 @@ Status VCollectIterator::next(IteratorRowRef* ref) {
 }
 
 Status VCollectIterator::next(Block* block) {
+    if (_topn_limit > 0) {
+        return topn_next(block);
+    }
+
     if (LIKELY(_inner_iter)) {
         return _inner_iter->next(block);
     } else {
         return Status::Error<END_OF_FILE>();
     }
 }
 
+Status VCollectIterator::topn_next(Block* block) {
+    if (_topn_eof) {
+        return Status::Error<END_OF_FILE>();
+    }
+
+    auto cloneBlock = block->clone_without_columns();

Review Comment:
   clone_block



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