ClickHouse/dbms/TableFunctions/TableFunctionMerge.cpp
2020-04-03 03:19:11 +03:00

90 lines
2.9 KiB
C++

#include <Common/OptimizedRegularExpression.h>
#include <Common/typeid_cast.h>
#include <Storages/StorageMerge.h>
#include <Parsers/ASTLiteral.h>
#include <Parsers/ASTFunction.h>
#include <TableFunctions/ITableFunction.h>
#include <Interpreters/evaluateConstantExpression.h>
#include <Interpreters/Context.h>
#include <Access/AccessFlags.h>
#include <TableFunctions/TableFunctionMerge.h>
#include <TableFunctions/TableFunctionFactory.h>
#include <TableFunctions/registerTableFunctions.h>
namespace DB
{
namespace ErrorCodes
{
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
extern const int UNKNOWN_TABLE;
}
static NamesAndTypesList chooseColumns(const String & source_database, const String & table_name_regexp_)
{
OptimizedRegularExpression table_name_regexp(table_name_regexp_);
auto table_name_match = [&](const String & table_name) { return table_name_regexp.match(table_name); };
StoragePtr any_table;
{
auto database = DatabaseCatalog::instance().getDatabase(source_database);
auto iterator = database->getTablesIterator(table_name_match);
if (iterator->isValid())
any_table = iterator->table();
}
if (!any_table)
throw Exception("Error while executing table function merge. In database " + source_database + " no one matches regular expression: "
+ table_name_regexp_, ErrorCodes::UNKNOWN_TABLE);
return any_table->getColumns().getAllPhysical();
}
StoragePtr TableFunctionMerge::executeImpl(const ASTPtr & ast_function, const Context & context, const std::string & table_name) const
{
ASTs & args_func = ast_function->children;
if (args_func.size() != 1)
throw Exception("Table function 'merge' requires exactly 2 arguments"
" - name of source database and regexp for table names.",
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
ASTs & args = args_func.at(0)->children;
if (args.size() != 2)
throw Exception("Table function 'merge' requires exactly 2 arguments"
" - name of source database and regexp for table names.",
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
args[0] = evaluateConstantExpressionForDatabaseName(args[0], context);
args[1] = evaluateConstantExpressionAsLiteral(args[1], context);
String source_database = args[0]->as<ASTLiteral &>().value.safeGet<String>();
String table_name_regexp = args[1]->as<ASTLiteral &>().value.safeGet<String>();
context.checkAccess(AccessType::merge, source_database);
auto res = StorageMerge::create(
StorageID(getDatabaseName(), table_name),
ColumnsDescription{chooseColumns(source_database, table_name_regexp)},
source_database,
table_name_regexp,
context);
res->startup();
return res;
}
void registerTableFunctionMerge(TableFunctionFactory & factory)
{
factory.registerFunction<TableFunctionMerge>();
}
}