ClickHouse/dbms/src/Interpreters/loadMetadata.cpp

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#include <Poco/DirectoryIterator.h>
#include <Poco/FileStream.h>
#include <DB/Parsers/ParserCreateQuery.h>
#include <DB/Parsers/ASTCreateQuery.h>
#include <DB/Interpreters/InterpreterCreateQuery.h>
#include <DB/Interpreters/loadMetadata.h>
#include <DB/IO/ReadBufferFromFile.h>
#include <DB/IO/WriteBufferFromString.h>
#include <DB/IO/copyData.h>
namespace DB
{
static void executeCreateQuery(const String & query, Context & context, const String & database, const String & file_name)
{
const char * begin = query.data();
const char * end = begin + query.size();
const char * pos = begin;
ParserCreateQuery parser;
ASTPtr ast;
String expected;
bool parse_res = parser.parse(pos, end, ast, expected);
/// Распарсенный запрос должен заканчиваться на конец входных данных или на точку с запятой.
if (!parse_res || (pos != end && *pos != ';'))
throw DB::Exception("Syntax error while executing query from file " + file_name + ": failed at position "
+ Poco::NumberFormatter::format(pos - begin) + ": "
+ std::string(pos, std::min(SHOW_CHARS_ON_SYNTAX_ERROR, end - pos))
+ ", expected " + (parse_res ? "end of query" : expected) + ".",
DB::ErrorCodes::SYNTAX_ERROR);
ASTCreateQuery & ast_create_query = dynamic_cast<ASTCreateQuery &>(*ast);
ast_create_query.attach = true;
ast_create_query.database = database;
InterpreterCreateQuery interpreter(ast, context);
interpreter.execute(true);
}
void loadMetadata(Context & context)
{
/// Здесь хранятся определения таблиц
String path = context.getPath() + "metadata";
/// Цикл по базам данных
Poco::DirectoryIterator dir_end;
for (Poco::DirectoryIterator it(path); it != dir_end; ++it)
{
if (!it->isDirectory())
continue;
/// Для директории .svn
if (it.name().at(0) == '.')
continue;
executeCreateQuery("ATTACH DATABASE " + it.name(), context, it.name(), it->path());
/// Цикл по таблицам
for (Poco::DirectoryIterator jt(it->path()); jt != dir_end; ++jt)
{
if (jt.name() == ".svn")
continue;
/// Файлы имеют имена вида table_name.sql
if (jt.name().compare(jt.name().size() - 4, 4, ".sql"))
throw Exception("Incorrect file extension: " + jt.name() + " in metadata directory " + it->path(), ErrorCodes::INCORRECT_FILE_NAME);
String s;
{
ReadBufferFromFile in(jt->path(), 32768);
WriteBufferFromString out(s);
copyData(in, out);
}
try
{
executeCreateQuery(s, context, it.name(), jt->path());
}
catch (const DB::Exception & e)
{
throw Exception("Cannot create table from metadata file " + jt->path() + ", error: " + e.displayText(),
ErrorCodes::CANNOT_CREATE_TABLE_FROM_METADATA);
}
}
}
}
}