HappenLee commented on code in PR #59263:
URL: https://github.com/apache/doris/pull/59263#discussion_r3315781492
##########
be/src/storage/segment/column_reader.cpp:
##########
@@ -1081,39 +1161,74 @@ Status MapFileColumnIterator::read_by_rowids(const
rowid_t* rowids, const size_t
if (count == 0) {
return Status::OK();
}
+
// resolve ColumnMap and nullable wrapper
auto& column_map = assert_cast<ColumnMap&, TypeCheckOnRelease::DISABLE>(
dst->is_nullable() ?
static_cast<ColumnNullable&>(*dst).get_nested_column() : *dst);
- auto offsets_ptr =
IColumn::mutate(std::move(column_map.get_offsets_ptr()));
- Defer defer_offsets {[&] { column_map.get_offsets_ptr() =
std::move(offsets_ptr); }};
+ const bool read_meta_columns = need_to_read_meta_columns();
+ MutableColumnPtr offsets_ptr;
+ if (read_meta_columns) {
+ offsets_ptr = IColumn::mutate(std::move(column_map.get_offsets_ptr()));
+ } else {
+ const auto base_offset =
+ column_map.get_offsets().empty() ? 0 :
column_map.get_offsets().back();
+ offsets_ptr = ColumnMap::COffsets::create();
+ assert_cast<ColumnOffset64&, TypeCheckOnRelease::DISABLE>(*offsets_ptr)
+ .insert_value(base_offset);
+ }
+ Defer defer_offsets {[&] {
+ if (read_meta_columns) {
+ column_map.get_offsets_ptr() = std::move(offsets_ptr);
+ }
+ }};
auto& offsets = static_cast<ColumnArray::ColumnOffsets&>(*offsets_ptr);
size_t base = offsets.get_data().empty() ? 0 : offsets.get_data().back();
// 1. bulk read null-map if nullable
std::vector<uint8_t> null_mask; // 0: not null, 1: null
- if (_map_reader->is_nullable()) {
- // For nullable map columns, the destination column must also be
nullable.
+ if (read_meta_columns) {
+ if (_map_reader->is_nullable()) {
+ // For nullable map columns, the destination column must also be
nullable.
+ if (UNLIKELY(!dst->is_nullable())) {
+ return Status::InternalError(
+ "unexpected non-nullable destination column for
nullable map reader");
+ }
+ MutableColumnPtr null_map_ptr =
+
static_cast<ColumnNullable&>(*dst).get_null_map_column_ptr();
+ size_t null_before = null_map_ptr->size();
+ RETURN_IF_ERROR(_null_iterator->read_by_rowids(rowids, count,
null_map_ptr));
+ // extract a light-weight view to decide element reads
+ auto& null_map_col = assert_cast<ColumnUInt8&>(*null_map_ptr);
+ null_mask.reserve(count);
+ for (size_t i = 0; i < count; ++i) {
+ null_mask.push_back(null_map_col.get_element(null_before + i));
+ }
+ } else if (dst->is_nullable()) {
+ // in not-null to null linked-schemachange mode,
+ // actually we do not change dat data include meta in footer,
+ // so may dst from changed meta which is nullable but old data is
not nullable,
+ // if so, we should set null_map to all null by default
+ MutableColumnPtr null_map_ptr =
+
static_cast<ColumnNullable&>(*dst).get_null_map_column_ptr();
+ auto& null_map = assert_cast<ColumnUInt8&>(*null_map_ptr);
+ null_map.insert_many_vals(0, count);
+ }
+ } else if (_map_reader->is_nullable()) {
+ // In lazy mode the parent null map has already been materialized
during predicate read.
+ // Read a temporary null map here only to compute child element ranges
correctly.
if (UNLIKELY(!dst->is_nullable())) {
return Status::InternalError(
"unexpected non-nullable destination column for nullable
map reader");
}
- auto null_map_ptr =
static_cast<ColumnNullable&>(*dst).get_null_map_column_ptr();
- size_t null_before = null_map_ptr->size();
- auto* null_map_col = null_map_ptr.get();
- MutableColumnPtr null_map_column = std::move(null_map_ptr);
- RETURN_IF_ERROR(_null_iterator->read_by_rowids(rowids, count,
null_map_column));
- // extract a light-weight view to decide element reads
+
+ MutableColumnPtr null_map_ptr = ColumnVector<TYPE_BOOLEAN>::create();
+ RETURN_IF_ERROR(_null_iterator->read_by_rowids(rowids, count,
null_map_ptr));
+
+ auto& null_map_col = assert_cast<ColumnUInt8&>(*null_map_ptr);
null_mask.reserve(count);
for (size_t i = 0; i < count; ++i) {
Review Comment:
better
```
const auto* src = null_map_col.get_data().data();
null_mask.assign(src, src + count);
```
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