wutiangan commented on a change in pull request #3993:
URL: https://github.com/apache/incubator-doris/pull/3993#discussion_r448288786
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File path: be/src/olap/generic_iterators.cpp
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@@ -227,8 +229,13 @@ class MergeIterator : public RowwiseIterator {
bool operator()(const MergeIteratorContext* lhs, const
MergeIteratorContext* rhs) const {
auto lhs_row = lhs->current_row();
auto rhs_row = rhs->current_row();
-
- return compare_row(lhs_row, rhs_row) > 0;
+ int cmp_res = compare_row(lhs_row, rhs_row);
+ if (cmp_res != 0) {
+ return cmp_res > 0;
+ }
+ // if row cursors equal, compare segment id.
Review comment:
add some comments why sort by row asc, and sort by segment_id desc.
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