ClickHouse/dbms/include/DB/Storages/MergeTree/MergeTreeDataSelectExecutor.h

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#pragma once
#include <DB/Storages/MergeTree/MergeTreeData.h>
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#include <DB/Storages/MergeTree/MergeTreeReader.h>
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namespace DB
{
/** Выполняет запросы SELECT на данных из merge-дерева.
*/
class MergeTreeDataSelectExecutor
{
public:
MergeTreeDataSelectExecutor(MergeTreeData & data_);
/** При чтении, выбирается набор кусков, покрывающий нужный диапазон индекса.
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* Если inout_part_index != nullptr, из этого счетчика берутся значения для виртуального столбца _part_index.
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*/
BlockInputStreams read(
const Names & column_names,
ASTPtr query,
const Context & context,
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const Settings & settings,
QueryProcessingStage::Enum & processed_stage,
size_t max_block_size = DEFAULT_BLOCK_SIZE,
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unsigned threads = 1,
size_t * inout_part_index = nullptr);
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private:
MergeTreeData & data;
Logger * log;
struct RangesInDataPart
{
MergeTreeData::DataPartPtr data_part;
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size_t part_index_in_query;
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MarkRanges ranges;
RangesInDataPart() {}
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RangesInDataPart(MergeTreeData::DataPartPtr data_part_, size_t part_index_in_query_)
: data_part(data_part_), part_index_in_query(part_index_in_query_)
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{
}
};
typedef std::vector<RangesInDataPart> RangesInDataParts;
BlockInputStreams spreadMarkRangesAmongThreads(
RangesInDataParts parts,
size_t threads,
const Names & column_names,
size_t max_block_size,
bool use_uncompressed_cache,
ExpressionActionsPtr prewhere_actions,
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const String & prewhere_column,
const Names & virt_columns,
const Settings & settings);
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BlockInputStreams spreadMarkRangesAmongThreadsFinal(
RangesInDataParts parts,
size_t threads,
const Names & column_names,
size_t max_block_size,
bool use_uncompressed_cache,
ExpressionActionsPtr prewhere_actions,
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const String & prewhere_column,
const Names & virt_columns,
const Settings & settings);
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/// Создать выражение "Sign == 1".
void createPositiveSignCondition(ExpressionActionsPtr & out_expression, String & out_column);
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MarkRanges markRangesFromPkRange(const MergeTreeData::DataPart::Index & index, PKCondition & key_condition, const Settings & settings);
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};
}