ClickHouse/src/Parsers/ASTQueryWithOnCluster.h

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#pragma once
#include <Parsers/IAST.h>
#include <Parsers/IParser.h>
namespace DB
{
/// Parameters for rewriting queries without ON CLUSTER, see getRewrittenASTWithoutOnCluster().
struct WithoutOnClusterASTRewriteParams
{
/// Default database from the cluster's configuration.
String default_database;
/// The ID of the current host in the format.
String host_id;
};
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/// TODO: Quite messy.
class ASTQueryWithOnCluster
{
public:
using Pos = IParser::Pos;
/// Should be parsed from ON CLUSTER <cluster> clause
String cluster;
/// new_database should be used by queries that refer to default db
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/// and default_database is specified for remote server
virtual ASTPtr getRewrittenASTWithoutOnCluster(const WithoutOnClusterASTRewriteParams & params = {}) const = 0; /// NOLINT
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/// Returns a query prepared for execution on remote server
std::string getRewrittenQueryWithoutOnCluster(const WithoutOnClusterASTRewriteParams & params = {}) const;
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void formatOnCluster(const IAST::FormatSettings & settings) const;
/// Parses " CLUSTER [cluster|'cluster'] " clause
static bool parse(Pos & pos, std::string & cluster_str, Expected & expected);
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virtual ~ASTQueryWithOnCluster() = default;
ASTQueryWithOnCluster() = default;
ASTQueryWithOnCluster(const ASTQueryWithOnCluster &) = default;
ASTQueryWithOnCluster & operator=(const ASTQueryWithOnCluster &) = default;
protected:
template <typename T>
static ASTPtr removeOnCluster(ASTPtr query_ptr, const std::string & new_database)
{
T & query = static_cast<T &>(*query_ptr);
query.cluster.clear();
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if (!query.database)
query.setDatabase(new_database);
return query_ptr;
}
template <typename T>
static ASTPtr removeOnCluster(ASTPtr query_ptr)
{
T & query = static_cast<T &>(*query_ptr);
query.cluster.clear();
return query_ptr;
}
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};
}