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42 lines
1.3 KiB
C++
42 lines
1.3 KiB
C++
#pragma once
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#include <Core/Names.h>
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#include <Processors/Chunk.h>
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namespace DB
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{
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/// Interface for entities with key-value semantics.
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class IKeyValueEntity
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{
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public:
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IKeyValueEntity() = default;
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virtual ~IKeyValueEntity() = default;
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/// Get primary key name that supports key-value requests.
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/// Primary key can constist of multiple columns.
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virtual Names getPrimaryKey() const = 0;
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/*
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* Get data from storage directly by keys.
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*
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* @param keys - keys to get data for. Key can be compound and represented by several columns.
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* @param out_null_map - output parameter indicating which keys were not found.
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* @param required_columns - if we don't need all attributes, implementation can use it to benefit from reading a subset of them.
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*
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* @return - chunk of data corresponding for keys.
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* Number of rows in chunk is equal to size of columns in keys.
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* If the key was not found row would have a default value.
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*/
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virtual Chunk getByKeys(const ColumnsWithTypeAndName & keys, PaddedPODArray<UInt8> & out_null_map, const Names & required_columns) const = 0;
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/// Header for getByKeys result
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virtual Block getSampleBlock(const Names & required_columns) const = 0;
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protected:
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/// Names of result columns. If empty then all columns are required.
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Names key_value_result_names;
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};
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}
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