ClickHouse/src/Core/ExternalTable.h
2021-05-31 17:49:02 +03:00

96 lines
2.7 KiB
C++

#pragma once
#include <Client/Connection.h>
#include <Core/Block.h>
#include <Interpreters/Context_fwd.h>
#include <IO/ReadBuffer.h>
#include <Server/HTTP/HTMLForm.h>
#include <iosfwd>
#include <memory>
#include <string>
#include <vector>
namespace Poco::Net
{
class NameValueCollection;
class MessageHeader;
}
namespace boost::program_options
{
class variables_map;
}
namespace DB
{
/// The base class containing the basic information about external table and
/// basic functions for extracting this information from text fields.
class BaseExternalTable
{
public:
std::string file; /// File with data or '-' if stdin
std::string name; /// The name of the table
std::string format; /// Name of the data storage format
/// Description of the table structure: (column name, data type name)
std::vector<std::pair<std::string, std::string>> structure;
std::unique_ptr<ReadBuffer> read_buffer;
Block sample_block;
virtual ~BaseExternalTable() = default;
/// Initialize read_buffer, depending on the data source. By default, does nothing.
virtual void initReadBuffer() {}
/// Get the table data - a pair (a stream with the contents of the table, the name of the table)
ExternalTableDataPtr getData(ContextPtr context);
protected:
/// Clear all accumulated information
void clear();
/// Construct the `structure` vector from the text field `structure`
virtual void parseStructureFromStructureField(const std::string & argument);
/// Construct the `structure` vector from the text field `types`
virtual void parseStructureFromTypesField(const std::string & argument);
private:
/// Initialize sample_block according to the structure of the table stored in the `structure`
void initSampleBlock();
};
/// Parsing of external table used in the tcp client.
class ExternalTable : public BaseExternalTable
{
public:
void initReadBuffer() override;
/// Extract parameters from variables_map, which is built on the client command line
explicit ExternalTable(const boost::program_options::variables_map & external_options);
};
/// Parsing of external table used when sending tables via http
/// The `handlePart` function will be called for each table passed,
/// so it's also necessary to call `clean` at the end of the `handlePart`.
class ExternalTablesHandler : public HTMLForm::PartHandler, BaseExternalTable, WithMutableContext
{
public:
ExternalTablesHandler(ContextMutablePtr context_, const Poco::Net::NameValueCollection & params_) : WithMutableContext(context_), params(params_) {}
void handlePart(const Poco::Net::MessageHeader & header, ReadBuffer & stream) override;
private:
const Poco::Net::NameValueCollection & params;
};
}