ClickHouse/dbms/programs/odbc-bridge/ColumnInfoHandler.cpp

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#include "ColumnInfoHandler.h"
#if USE_POCO_SQLODBC || USE_POCO_DATAODBC
#include <Poco/Data/ODBC/ODBCException.h>
#include <Poco/Data/ODBC/SessionImpl.h>
#include <Poco/Data/ODBC/Utility.h>
#include <Poco/Net/HTTPServerRequest.h>
#include <Poco/Net/HTTPServerResponse.h>
#include <DataTypes/DataTypeFactory.h>
#include <IO/WriteBufferFromHTTPServerResponse.h>
#include <IO/WriteHelpers.h>
#include <Common/HTMLForm.h>
#include <Parsers/ParserQueryWithOutput.h>
#include <Parsers/parseQuery.h>
#include <common/logger_useful.h>
#include <ext/scope_guard.h>
#include "validateODBCConnectionString.h"
namespace DB
{
namespace
{
DataTypePtr getDataType(SQLSMALLINT type)
{
const auto & factory = DataTypeFactory::instance();
switch (type)
{
case SQL_INTEGER:
return factory.get("Int32");
case SQL_SMALLINT:
return factory.get("Int16");
case SQL_FLOAT:
return factory.get("Float32");
case SQL_REAL:
return factory.get("Float32");
case SQL_DOUBLE:
return factory.get("Float64");
case SQL_DATETIME:
return factory.get("DateTime");
case SQL_TYPE_TIMESTAMP:
return factory.get("DateTime");
case SQL_TYPE_DATE:
return factory.get("Date");
default:
return factory.get("String");
}
}
}
void ODBCColumnsInfoHandler::handleRequest(Poco::Net::HTTPServerRequest & request, Poco::Net::HTTPServerResponse & response)
{
Poco::Net::HTMLForm params(request, request.stream());
LOG_TRACE(log, "Request URI: " + request.getURI());
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auto process_error = [&response, this](const std::string & message)
{
response.setStatusAndReason(Poco::Net::HTTPResponse::HTTP_INTERNAL_SERVER_ERROR);
if (!response.sent())
response.send() << message << std::endl;
LOG_WARNING(log, message);
};
if (!params.has("table"))
{
process_error("No 'table' param in request URL");
return;
}
if (!params.has("connection_string"))
{
process_error("No 'connection_string' in request URL");
return;
}
std::string schema_name = "";
std::string table_name = params.get("table");
std::string connection_string = params.get("connection_string");
if (params.has("schema"))
{
schema_name = params.get("schema");
LOG_TRACE(log, "Will fetch info for table '" << schema_name + "." + table_name << "'");
} else
LOG_TRACE(log, "Will fetch info for table '" << table_name << "'");
LOG_TRACE(log, "Got connection str '" << connection_string << "'");
try
{
Poco::Data::ODBC::SessionImpl session(validateODBCConnectionString(connection_string), DBMS_DEFAULT_CONNECT_TIMEOUT_SEC);
SQLHDBC hdbc = session.dbc().handle();
SQLHSTMT hstmt = nullptr;
if (Poco::Data::ODBC::Utility::isError(SQLAllocStmt(hdbc, &hstmt)))
throw Poco::Data::ODBC::ODBCException("Could not allocate connection handle.");
SCOPE_EXIT(SQLFreeStmt(hstmt, SQL_DROP));
/// TODO Why not do SQLColumns instead?
std::string name = schema_name.empty() ? table_name : schema_name + "." + table_name;
std::stringstream ss;
std::string input = "SELECT * FROM " + name + " WHERE 1 = 0";
ParserQueryWithOutput parser;
ASTPtr select = parseQuery(parser, input.data(), input.data() + input.size(), "", 0);
IAST::FormatSettings settings(ss, true);
settings.always_quote_identifiers = true;
settings.identifier_quoting_style = IdentifierQuotingStyle::DoubleQuotes;
select->format(settings);
std::string query = ss.str();
if (Poco::Data::ODBC::Utility::isError(Poco::Data::ODBC::SQLPrepare(hstmt, reinterpret_cast<SQLCHAR *>(query.data()), query.size())))
throw Poco::Data::ODBC::DescriptorException(session.dbc());
if (Poco::Data::ODBC::Utility::isError(SQLExecute(hstmt)))
throw Poco::Data::ODBC::StatementException(hstmt);
SQLSMALLINT cols = 0;
if (Poco::Data::ODBC::Utility::isError(SQLNumResultCols(hstmt, &cols)))
throw Poco::Data::ODBC::StatementException(hstmt);
/// TODO cols not checked
NamesAndTypesList columns;
for (SQLSMALLINT ncol = 1; ncol <= cols; ++ncol)
{
SQLSMALLINT type = 0;
/// TODO Why 301?
SQLCHAR column_name[301];
/// TODO Result is not checked.
Poco::Data::ODBC::SQLDescribeCol(hstmt, ncol, column_name, sizeof(column_name), nullptr, &type, nullptr, nullptr, nullptr);
columns.emplace_back(reinterpret_cast<char *>(column_name), getDataType(type));
}
WriteBufferFromHTTPServerResponse out(request, response, keep_alive_timeout);
writeStringBinary(columns.toString(), out);
}
catch (...)
{
process_error("Error getting columns from ODBC '" + getCurrentExceptionMessage(false) + "'");
tryLogCurrentException(log);
}
}
}
#endif