ClickHouse/src/Storages/MergeTree/MergeTreeDataPartInMemory.h
Amos Bird 264cff6415
Projections
TODO (suggested by Nikolai)

1. Build query plan fro current query (inside storage::read) up to WithMergableState
2. Check, that plan is simple enough: Aggregating - Expression - Filter - ReadFromStorage (or simplier)
3. Check, that filter is the same as filter in projection, and also expression calculates the same aggregation keys as in projection
4. Return WithMergableState if projection applies

3 will be easier to do with ActionsDAG, cause it sees all functions, and dependencies are direct (but it is possible with ExpressionActions also)

Also need to figure out how prewhere works for projections, and
row_filter_policies.

wip
2021-05-11 18:12:23 +08:00

70 lines
2.6 KiB
C++

#pragma once
#include <Storages/MergeTree/IMergeTreeDataPart.h>
namespace DB
{
class UncompressedCache;
class MergeTreeDataPartInMemory : public IMergeTreeDataPart
{
public:
MergeTreeDataPartInMemory(
const MergeTreeData & storage_,
const String & name_,
const MergeTreePartInfo & info_,
const VolumePtr & volume_,
const std::optional<String> & relative_path_ = {},
const IMergeTreeDataPart * parent_part_ = nullptr);
MergeTreeDataPartInMemory(
MergeTreeData & storage_,
const String & name_,
const VolumePtr & volume_,
const std::optional<String> & relative_path_ = {},
const IMergeTreeDataPart * parent_part_ = nullptr);
MergeTreeReaderPtr getReader(
const NamesAndTypesList & columns,
const StorageMetadataPtr & metadata_snapshot,
const MarkRanges & mark_ranges,
UncompressedCache * uncompressed_cache,
MarkCache * mark_cache,
const MergeTreeReaderSettings & reader_settings_,
const ValueSizeMap & avg_value_size_hints,
const ReadBufferFromFileBase::ProfileCallback & profile_callback) const override;
MergeTreeWriterPtr getWriter(
const NamesAndTypesList & columns_list,
const StorageMetadataPtr & metadata_snapshot,
const std::vector<MergeTreeIndexPtr> & indices_to_recalc,
const CompressionCodecPtr & default_codec_,
const MergeTreeWriterSettings & writer_settings,
const MergeTreeIndexGranularity & computed_index_granularity) const override;
bool isStoredOnDisk() const override { return false; }
bool hasColumnFiles(const NameAndTypePair & column) const override { return !!getColumnPosition(column.name); }
String getFileNameForColumn(const NameAndTypePair & /* column */) const override { return ""; }
void renameTo(const String & new_relative_path, bool remove_new_dir_if_exists) const override;
void makeCloneInDetached(const String & prefix, const StorageMetadataPtr & metadata_snapshot) const override;
void flushToDisk(const String & base_path, const String & new_relative_path, const StorageMetadataPtr & metadata_snapshot) const;
/// Returns hash of parts's block
Checksum calculateBlockChecksum() const;
mutable Block block;
private:
mutable std::condition_variable is_merged;
/// Calculates uncompressed sizes in memory.
void calculateEachColumnSizes(ColumnSizeByName & each_columns_size, ColumnSize & total_size) const override;
};
using DataPartInMemoryPtr = std::shared_ptr<const MergeTreeDataPartInMemory>;
DataPartInMemoryPtr asInMemoryPart(const MergeTreeDataPartPtr & part);
}