ClickHouse/src/TableFunctions/TableFunctionGenerateRandom.cpp
2021-04-23 12:18:23 +00:00

99 lines
3.2 KiB
C++

#include <Common/typeid_cast.h>
#include <Common/Exception.h>
#include <Core/Block.h>
#include <Storages/StorageGenerateRandom.h>
#include <Parsers/ASTExpressionList.h>
#include <Parsers/ASTLiteral.h>
#include <Parsers/ASTFunction.h>
#include <TableFunctions/ITableFunction.h>
#include <TableFunctions/TableFunctionFactory.h>
#include <TableFunctions/TableFunctionGenerateRandom.h>
#include <TableFunctions/parseColumnsListForTableFunction.h>
#include "registerTableFunctions.h"
namespace DB
{
namespace ErrorCodes
{
extern const int BAD_ARGUMENTS;
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
extern const int LOGICAL_ERROR;
}
void TableFunctionGenerateRandom::parseArguments(const ASTPtr & ast_function, ContextPtr /*context*/)
{
ASTs & args_func = ast_function->children;
if (args_func.size() != 1)
throw Exception("Table function '" + getName() + "' must have arguments.", ErrorCodes::LOGICAL_ERROR);
ASTs & args = args_func.at(0)->children;
if (args.empty())
throw Exception("Table function '" + getName() + "' requires at least one argument: "
" structure, [random_seed, max_string_length, max_array_length].",
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
if (args.size() > 4)
throw Exception("Table function '" + getName() + "' requires at most four arguments: "
" structure, [random_seed, max_string_length, max_array_length].",
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
// All the arguments must be literals.
for (const auto & arg : args)
{
if (!arg->as<const ASTLiteral>())
{
throw Exception(fmt::format(
"All arguments of table function '{}' must be literals. "
"Got '{}' instead", getName(), arg->formatForErrorMessage()),
ErrorCodes::BAD_ARGUMENTS);
}
}
/// Parsing first argument as table structure and creating a sample block
structure = args[0]->as<const ASTLiteral &>().value.safeGet<String>();
if (args.size() >= 2)
{
const Field & value = args[1]->as<const ASTLiteral &>().value;
if (!value.isNull())
random_seed = value.safeGet<UInt64>();
}
if (args.size() >= 3)
max_string_length = args[2]->as<const ASTLiteral &>().value.safeGet<UInt64>();
if (args.size() == 4)
max_array_length = args[3]->as<const ASTLiteral &>().value.safeGet<UInt64>();
}
ColumnsDescription TableFunctionGenerateRandom::getActualTableStructure(ContextPtr context) const
{
return parseColumnsListFromString(structure, context);
}
StoragePtr TableFunctionGenerateRandom::executeImpl(const ASTPtr & /*ast_function*/, ContextPtr context, const std::string & table_name, ColumnsDescription /*cached_columns*/) const
{
auto columns = getActualTableStructure(context);
auto res = StorageGenerateRandom::create(
StorageID(getDatabaseName(), table_name), columns, String{}, max_array_length, max_string_length, random_seed);
res->startup();
return res;
}
void registerTableFunctionGenerate(TableFunctionFactory & factory)
{
factory.registerFunction<TableFunctionGenerateRandom>();
}
}