ClickHouse/src/Core/BlockInfo.h
2022-05-18 09:25:26 +00:00

76 lines
2.5 KiB
C++

#pragma once
#include <base/types.h>
#include <unordered_map>
#include <vector>
namespace DB
{
class ReadBuffer;
class WriteBuffer;
/** More information about the block.
*/
struct BlockInfo
{
/** is_overflows:
* After running GROUP BY ... WITH TOTALS with the max_rows_to_group_by and group_by_overflow_mode = 'any' settings,
* a row is inserted in the separate block with aggregated values that have not passed max_rows_to_group_by.
* If it is such a block, then is_overflows is set to true for it.
*/
/** bucket_num:
* When using the two-level aggregation method, data with different key groups are scattered across different buckets.
* In this case, the bucket number is indicated here. It is used to optimize the merge for distributed aggregation.
* Otherwise -1.
*/
#define APPLY_FOR_BLOCK_INFO_FIELDS(M) \
M(bool, is_overflows, false, 1) \
M(Int32, bucket_num, -1, 2)
#define DECLARE_FIELD(TYPE, NAME, DEFAULT, FIELD_NUM) \
TYPE NAME = DEFAULT;
APPLY_FOR_BLOCK_INFO_FIELDS(DECLARE_FIELD)
#undef DECLARE_FIELD
/// Write the values in binary form. NOTE: You could use protobuf, but it would be overkill for this case.
void write(WriteBuffer & out) const;
/// Read the values in binary form.
void read(ReadBuffer & in);
};
/// Block extension to support delayed defaults. AddingDefaultsTransform uses it to replace missing values with column defaults.
class BlockMissingValues
{
public:
using RowsBitMask = std::vector<bool>; /// a bit per row for a column
/// Get mask for column, column_idx is index inside corresponding block
const RowsBitMask & getDefaultsBitmask(size_t column_idx) const;
/// Check that we have to replace default value at least in one of columns
bool hasDefaultBits(size_t column_idx) const;
/// Set bit for a specified row in a single column.
void setBit(size_t column_idx, size_t row_idx);
/// Set bits for all rows in a single column.
void setBits(size_t column_idx, size_t rows);
bool empty() const { return rows_mask_by_column_id.empty(); }
size_t size() const { return rows_mask_by_column_id.size(); }
void clear() { rows_mask_by_column_id.clear(); }
private:
using RowsMaskByColumnId = std::unordered_map<size_t, RowsBitMask>;
/// If rows_mask_by_column_id[column_id][row_id] is true related value in Block should be replaced with column default.
/// It could contain less columns and rows then related block.
RowsMaskByColumnId rows_mask_by_column_id;
};
}