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[Improvement](segment iterator) Optimize column row reservation to reduce overhead #42060 #42372

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Merged
airborne12 merged 1 commit into from
Oct 24, 2024
Merged

[Improvement](segment iterator) Optimize column row reservation to reduce overhead #42060 #42372

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10 changes: 7 additions & 3 deletions be/src/olap/rowset/segment_v2/segment_iterator.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1987,6 +1987,9 @@ Status SegmentIterator::_next_batch_internal(vectorized::Block* block) {
if (UNLIKELY(!_lazy_inited)) {
RETURN_IF_ERROR(_lazy_init());
_lazy_inited = true;
// If the row bitmap size is smaller than block_row_max, there's no need to reserve that many column rows.
auto nrows_reserve_limit =
std::min(_row_bitmap.cardinality(), uint64_t(_opts.block_row_max));
if (_lazy_materialization_read || _opts.record_rowids || _is_need_expr_eval) {
_block_rowids.resize(_opts.block_row_max);
}
Expand All @@ -2011,7 +2014,7 @@ Status SegmentIterator::_next_batch_internal(vectorized::Block* block) {
storage_column_type->is_nullable(), _opts.io_ctx.reader_type));
_current_return_columns[cid]->set_rowset_segment_id(
{_segment->rowset_id(), _segment->id()});
_current_return_columns[cid]->reserve(_opts.block_row_max);
_current_return_columns[cid]->reserve(nrows_reserve_limit);
} else if (i >= block->columns()) {
// if i >= block->columns means the column and not the pred_column means `column i` is
// a delete condition column. but the column is not effective in the segment. so we just
Expand All @@ -2022,7 +2025,7 @@ Status SegmentIterator::_next_batch_internal(vectorized::Block* block) {
// TODO: skip read the not effective delete column to speed up segment read.
_current_return_columns[cid] =
Schema::get_data_type_ptr(*column_desc)->create_column();
_current_return_columns[cid]->reserve(_opts.block_row_max);
_current_return_columns[cid]->reserve(nrows_reserve_limit);
}
}

Expand All @@ -2047,7 +2050,8 @@ Status SegmentIterator::_next_batch_internal(vectorized::Block* block) {
if (_can_opt_topn_reads()) {
nrows_read_limit = std::min(static_cast<uint32_t>(_opts.topn_limit), nrows_read_limit);
}

// If the row bitmap size is smaller than nrows_read_limit, there's no need to reserve that many column rows.
nrows_read_limit = std::min(_row_bitmap.cardinality(), uint64_t(nrows_read_limit));
DBUG_EXECUTE_IF("segment_iterator.topn_opt_1", {
if (nrows_read_limit != 1) {
return Status::Error<ErrorCode::INTERNAL_ERROR>("topn opt 1 execute failed: {}",
Expand Down