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#pragma once
#include <TableFunctions/ITableFunction.h>
#include <Interpreters/Cluster.h>
#include <Interpreters/StorageID.h>
namespace DB
{
/* remote ('address', db, table) - creates a temporary StorageDistributed.
* To get the table structure, a DESC TABLE request is made to the remote server.
* For example:
* SELECT count() FROM remote('example01-01-1', merge, hits) - go to `example01-01-1`, in the merge database, the hits table.
* An expression that generates a set of shards and replicas can also be specified as the host name - see below.
* Also, there is a cluster version of the function: cluster('existing_cluster_name', 'db', 'table').
*/
class TableFunctionRemote : public ITableFunction
{
public:
explicit TableFunctionRemote(const std::string & name_, bool secure_ = false);
std::string getName() const override { return name; }
ColumnsDescription getActualTableStructure(ContextPtr context, bool is_insert_query) const override;
bool needStructureConversion() const override { return false; }
private:
StoragePtr executeImpl(const ASTPtr & ast_function, ContextPtr context, const std::string & table_name, ColumnsDescription cached_columns, bool is_insert_query) const override;
const char * getStorageTypeName() const override { return "Distributed"; }
void parseArguments(const ASTPtr & ast_function, ContextPtr context) override;
std::string name;
bool is_cluster_function;
PreformattedMessage help_message;
bool secure;
ClusterPtr cluster;
StorageID remote_table_id = StorageID::createEmpty();
ASTPtr remote_table_function_ptr;
ASTPtr sharding_key = nullptr;
};
}
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