Re: [PR] [feature](scan) Implement parallel scanning by dividing the tablets based on either the row range or the key range. [doris]

[via GitHub]

yiguolei commented on code in PR #28103:
URL: https://github.com/apache/doris/pull/28103#discussion_r1435914069


##########
be/src/olap/rowset/segment_v2/segment_iterator.cpp:
##########
@@ -392,35 +396,57 @@ Status SegmentIterator::_get_row_ranges_by_keys() {
     DorisMetrics::instance()->segment_row_total->increment(num_rows());
 
     // fast path for empty segment or empty key ranges
-    if (_row_bitmap.isEmpty() || _opts.key_ranges.empty()) {
-        return Status::OK();
-    }
-
-    // Read & seek key columns is a waste of time when no key column in _schema
-    if (std::none_of(_schema->columns().begin(), _schema->columns().end(), 
[&](const Field* col) {
-            return col && 
_opts.tablet_schema->column_by_uid(col->unique_id()).is_key();
-        })) {
+    if (_row_bitmap.isEmpty() || (!_opts.split_key_range.valid && 
_opts.key_ranges.empty())) {
         return Status::OK();
     }
 
     RowRanges result_ranges;
-    for (auto& key_range : _opts.key_ranges) {
+    if (_opts.split_key_range.valid) {

Review Comment:
   key range：
   1. scan key keyrange
   2. where short key ---> key range
   add comment



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