github-actions[bot] commented on code in PR #66849:
URL: https://github.com/apache/doris/pull/66849#discussion_r3796864535
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be/src/storage/iterator/block_reader.cpp:
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@@ -95,6 +110,10 @@ Status BlockReader::_ensure_binlog_column_pos(const Block&
src_block) {
const uint32_t col_num = src_block.columns();
_before_column_idx.resize(col_num);
+ std::iota(_before_column_idx.begin(), _before_column_idx.end(), 0);
+ std::vector<bool> is_before_value_column(col_num, false);
Review Comment:
[P1] Build the name map once before resolving mirrors. MIN_DELTA now feeds
every AFTER and BEFORE column into this block, but the loop below calls
Block::get_position_by_name()--an O(C) scan--for each physical column. A table
with V values has roughly 2V value/mirror columns, so every BlockReader
performs O(C^2) string comparisons, repeated per tablet scanner. Please use
Block::get_name_to_pos_map() once here and resolve every BEFORE name from it.
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