stdpain commented on a change in pull request #5313:
URL: https://github.com/apache/incubator-doris/pull/5313#discussion_r567629275
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File path: be/src/exec/topn_node.h
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@@ -101,12 +102,8 @@ class TopNNode : public ExecNode {
// Number of rows skipped. Used for adhering to _offset.
int64_t _num_rows_skipped;
- // The priority queue will never have more elements in it than the LIMIT.
The stl
- // priority queue doesn't support a max size, so to get that
functionality, the order
- // of the queue is the opposite of what the ORDER BY clause specifies,
such that the top
- // of the queue is the last sorted element.
- boost::scoped_ptr<std::priority_queue<Tuple*, std::vector<Tuple*>,
TupleRowComparator>>
- _priority_queue;
+ // The priority queue will never have more elements in it than the LIMIT.
+ std::unique_ptr<SortingHeap<Tuple*, std::vector<Tuple*>,
TupleRowComparator>> _priority_queue;
Review comment:
SortingHeap is essentially a priority queue, but with a replace_top
interface, so naming it as a priority queue is more friendly to people who come
into contact with this code for the first time
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