imay commented on a change in pull request #764: Convert next_row interface to
next_block
URL: https://github.com/apache/incubator-doris/pull/764#discussion_r266929641
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File path: be/src/olap/rowset/alpha_rowset_reader.cpp
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@@ -54,66 +48,57 @@ OLAPStatus AlphaRowsetReader::init(RowsetReaderContext*
read_context) {
_dst_cursor = new(std::nothrow)RowCursor();
_dst_cursor->init(*(_current_read_context->tablet_schema));
OLAPStatus status = _init_column_datas(read_context);
- return status;
-}
-bool AlphaRowsetReader::has_next() {
- bool next_flag = false;
- for (int i = 0; i < _column_datas.size(); ++i) {
- auto& row_block = _row_blocks[i];
- if (row_block != nullptr) {
- if (row_block->has_remaining()) {
- next_flag = true;
+ Version version = _alpha_rowset_meta->version();
+ _is_singleton_rowset = (version.first == version.second);
+ bool merge = false;
+ /*
+ * For singleton rowset, there exists three situations.
+ * 1. DUP_KEYS tablet has no necessities to merge row in advance.
+ * 2. COMPACTION/CHECKSUM/ALTER_TABLET task has no necessities to
+ * merge row in advance.
+ * 3. QUERY task will set preaggregation. If preaggregation is
+ * set to be true, it is necessary to merge row in advance.
+ * For cumulative rowset, there is no necessities to merge row in advance.
+ */
+ if (_is_singleton_rowset) {
+ if (_current_read_context->tablet_schema->keys_type() == DUP_KEYS) {
+ // DUP_KEYS tablet
+ _next_block =
&AlphaRowsetReader::_next_block_for_singleton_without_merge;
+ } else {
+ if (_current_read_context->reader_type == READER_QUERY
+ && _current_read_context->preaggregation) {
+ // QUERY task which set preaggregation to be true.
+ _next_block =
&AlphaRowsetReader::_next_block_for_singleton_with_merge;
Review comment:
when `preaggregation` is set to true, we read data without merge
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