ClickHouse/src/Storages/MergeTree/MergeTreeDataSelectExecutor.h
Amos Bird d901ead1bc
Done
2022-11-04 17:26:44 +08:00

224 lines
8.9 KiB
C++

#pragma once
#include <Core/QueryProcessingStage.h>
#include <Storages/SelectQueryInfo.h>
#include <Storages/MergeTree/MergeTreeData.h>
#include <Storages/MergeTree/RangesInDataPart.h>
#include <Storages/MergeTree/PartitionPruner.h>
#include <Processors/QueryPlan/ReadFromMergeTree.h>
namespace DB
{
class KeyCondition;
struct QueryIdHolder;
using PartitionIdToMaxBlock = std::unordered_map<String, Int64>;
/** Executes SELECT queries on data from the merge tree.
*/
class MergeTreeDataSelectExecutor
{
public:
explicit MergeTreeDataSelectExecutor(const MergeTreeData & data_);
/** When reading, selects a set of parts that covers the desired range of the index.
* max_blocks_number_to_read - if not nullptr, do not read all the parts whose right border is greater than max_block in partition.
*/
QueryPlanPtr read(
const Names & column_names,
const StorageSnapshotPtr & storage_snapshot,
const SelectQueryInfo & query_info,
ContextPtr context,
UInt64 max_block_size,
size_t num_streams,
QueryProcessingStage::Enum processed_stage,
std::shared_ptr<PartitionIdToMaxBlock> max_block_numbers_to_read = nullptr,
bool enable_parallel_reading = false) const;
/// The same as read, but with specified set of parts.
QueryPlanPtr readFromParts(
MergeTreeData::DataPartsVector parts,
const Names & column_names,
const StorageSnapshotPtr & storage_snapshot,
const SelectQueryInfo & query_info,
ContextPtr context,
UInt64 max_block_size,
size_t num_streams,
std::shared_ptr<PartitionIdToMaxBlock> max_block_numbers_to_read = nullptr,
MergeTreeDataSelectAnalysisResultPtr merge_tree_select_result_ptr = nullptr,
bool enable_parallel_reading = false) const;
/// Get an estimation for the number of marks we are going to read.
/// Reads nothing. Secondary indexes are not used.
/// This method is used to select best projection for table.
MergeTreeDataSelectAnalysisResultPtr estimateNumMarksToRead(
MergeTreeData::DataPartsVector parts,
const PrewhereInfoPtr & prewhere_info,
const Names & column_names,
const StorageMetadataPtr & metadata_snapshot_base,
const StorageMetadataPtr & metadata_snapshot,
const SelectQueryInfo & query_info,
const ActionDAGNodes & added_filter_nodes,
ContextPtr context,
size_t num_streams,
std::shared_ptr<PartitionIdToMaxBlock> max_block_numbers_to_read = nullptr) const;
private:
const MergeTreeData & data;
Poco::Logger * log;
/// Get the approximate value (bottom estimate - only by full marks) of the number of rows falling under the index.
static size_t getApproximateTotalRowsToRead(
const MergeTreeData::DataPartsVector & parts,
const StorageMetadataPtr & metadata_snapshot,
const KeyCondition & key_condition,
const Settings & settings,
Poco::Logger * log);
static MarkRanges markRangesFromPKRange(
const MergeTreeData::DataPartPtr & part,
const StorageMetadataPtr & metadata_snapshot,
const KeyCondition & key_condition,
const Settings & settings,
Poco::Logger * log);
static MarkRanges filterMarksUsingIndex(
MergeTreeIndexPtr index_helper,
MergeTreeIndexConditionPtr condition,
MergeTreeData::DataPartPtr part,
const MarkRanges & ranges,
const Settings & settings,
const MergeTreeReaderSettings & reader_settings,
size_t & total_granules,
size_t & granules_dropped,
MarkCache * mark_cache,
UncompressedCache * uncompressed_cache,
Poco::Logger * log);
static MarkRanges filterMarksUsingMergedIndex(
MergeTreeIndices indices,
MergeTreeIndexMergedConditionPtr condition,
MergeTreeData::DataPartPtr part,
const MarkRanges & ranges,
const Settings & settings,
const MergeTreeReaderSettings & reader_settings,
size_t & total_granules,
size_t & granules_dropped,
MarkCache * mark_cache,
UncompressedCache * uncompressed_cache,
Poco::Logger * log);
struct PartFilterCounters
{
size_t num_initial_selected_parts = 0;
size_t num_initial_selected_granules = 0;
size_t num_parts_after_minmax = 0;
size_t num_granules_after_minmax = 0;
size_t num_parts_after_partition_pruner = 0;
size_t num_granules_after_partition_pruner = 0;
};
/// Select the parts in which there can be data that satisfy `minmax_idx_condition` and that match the condition on `_part`,
/// as well as `max_block_number_to_read`.
static void selectPartsToRead(
MergeTreeData::DataPartsVector & parts,
const std::optional<std::unordered_set<String>> & part_values,
const std::optional<KeyCondition> & minmax_idx_condition,
const DataTypes & minmax_columns_types,
std::optional<PartitionPruner> & partition_pruner,
const PartitionIdToMaxBlock * max_block_numbers_to_read,
PartFilterCounters & counters);
/// Same as previous but also skip parts uuids if any to the query context, or skip parts which uuids marked as excluded.
static void selectPartsToReadWithUUIDFilter(
MergeTreeData::DataPartsVector & parts,
const std::optional<std::unordered_set<String>> & part_values,
MergeTreeData::PinnedPartUUIDsPtr pinned_part_uuids,
const std::optional<KeyCondition> & minmax_idx_condition,
const DataTypes & minmax_columns_types,
std::optional<PartitionPruner> & partition_pruner,
const PartitionIdToMaxBlock * max_block_numbers_to_read,
ContextPtr query_context,
PartFilterCounters & counters,
Poco::Logger * log);
public:
/// For given number rows and bytes, get the number of marks to read.
/// It is a minimal number of marks which contain so many rows and bytes.
static size_t roundRowsOrBytesToMarks(
size_t rows_setting,
size_t bytes_setting,
size_t rows_granularity,
size_t bytes_granularity);
/// The same as roundRowsOrBytesToMarks, but return no more than max_marks.
static size_t minMarksForConcurrentRead(
size_t rows_setting,
size_t bytes_setting,
size_t rows_granularity,
size_t bytes_granularity,
size_t max_marks);
/// If possible, filter using expression on virtual columns.
/// Example: SELECT count() FROM table WHERE _part = 'part_name'
/// If expression found, return a set with allowed part names (std::nullopt otherwise).
static std::optional<std::unordered_set<String>> filterPartsByVirtualColumns(
const MergeTreeData & data,
const MergeTreeData::DataPartsVector & parts,
const ASTPtr & query,
ContextPtr context);
/// Filter parts using minmax index and partition key.
static void filterPartsByPartition(
MergeTreeData::DataPartsVector & parts,
const std::optional<std::unordered_set<String>> & part_values,
const StorageMetadataPtr & metadata_snapshot,
const MergeTreeData & data,
const SelectQueryInfo & query_info,
const ContextPtr & context,
const PartitionIdToMaxBlock * max_block_numbers_to_read,
Poco::Logger * log,
ReadFromMergeTree::IndexStats & index_stats);
/// Filter parts using primary key and secondary indexes.
/// For every part, select mark ranges to read.
/// If 'check_limits = true' it will throw exception if the amount of data exceed the limits from settings.
static RangesInDataParts filterPartsByPrimaryKeyAndSkipIndexes(
MergeTreeData::DataPartsVector && parts,
StorageMetadataPtr metadata_snapshot,
const SelectQueryInfo & query_info,
const ContextPtr & context,
const KeyCondition & key_condition,
const MergeTreeReaderSettings & reader_settings,
Poco::Logger * log,
size_t num_streams,
ReadFromMergeTree::IndexStats & index_stats,
bool use_skip_indexes);
/// Create expression for sampling.
/// Also, calculate _sample_factor if needed.
/// Also, update key condition with selected sampling range.
static MergeTreeDataSelectSamplingData getSampling(
const SelectQueryInfo & select_query_info,
NamesAndTypesList available_real_columns,
const MergeTreeData::DataPartsVector & parts,
KeyCondition & key_condition,
const MergeTreeData & data,
const StorageMetadataPtr & metadata_snapshot,
ContextPtr context,
bool sample_factor_column_queried,
Poco::Logger * log);
/// Check query limits: max_partitions_to_read, max_concurrent_queries.
/// Also, return QueryIdHolder. If not null, we should keep it until query finishes.
static std::shared_ptr<QueryIdHolder> checkLimits(
const MergeTreeData & data,
const ReadFromMergeTree::AnalysisResult & result,
const ContextPtr & context);
};
}