ClickHouse/dbms/include/DB/Interpreters/ClusterProxy/Query.h

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#pragma once
#include <DB/Parsers/IAST.h>
#include <DB/Storages/IStorage.h>
#include <DB/Interpreters/Cluster.h>
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namespace DB
{
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struct Settings;
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class Context;
class Cluster;
namespace ClusterProxy
{
class IQueryConstructor;
/// This class is designed for distributed queries execution. It hides from
/// the caller the details about the actual locations at which a distributed
/// query is performed. Depending on the type of query to be performed,
/// (currently SELECT, DESCRIBE, or ALTER (for resharding)), a so-called
/// query constructor is specified. Such an object states, among other things,
/// how connections must be allocated for remote execution.
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class Query
{
public:
Query(IQueryConstructor & query_constructor_, const ClusterPtr & cluster_,
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ASTPtr query_ast_, const Context & context_, const Settings & settings_, bool enable_shard_multiplexing_);
/// For each location at which we perform the query, create an input stream
/// from which we can fetch the result.
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BlockInputStreams execute();
private:
IQueryConstructor & query_constructor;
ClusterPtr cluster;
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ASTPtr query_ast;
const Context & context;
const Settings & settings;
bool enable_shard_multiplexing;
};
}
}