ClickHouse/dbms/include/DB/Storages/System/StorageSystemClusters.h

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#pragma once
#include <ext/shared_ptr_helper.hpp>
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#include <DB/Storages/IStorage.h>
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namespace DB
{
class Context;
/** Implements system table 'clusters'
* that allows to obtain information about available clusters
* (which may be specified in Distributed tables).
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*/
class StorageSystemClusters : private ext::shared_ptr_helper<StorageSystemClusters>, public IStorage
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{
friend class ext::shared_ptr_helper<StorageSystemClusters>;
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public:
StorageSystemClusters(const std::string & name_, Context & context_);
static StoragePtr create(const std::string & name_, Context & context_);
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std::string getName() const override { return "SystemClusters"; }
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std::string getTableName() const override { return name; }
const NamesAndTypesList & getColumnsListImpl() const override { return columns; }
BlockInputStreams read(
const Names & column_names,
ASTPtr query,
const Context & context,
const Settings & settings,
QueryProcessingStage::Enum & processed_stage,
size_t max_block_size = DEFAULT_BLOCK_SIZE,
unsigned threads = 1) override;
private:
StorageSystemClusters(const std::string & name_);
private:
const std::string name;
NamesAndTypesList columns;
Context & context;
};
}