ClickHouse/src/Functions/UTCTimestamp.cpp

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#include <DataTypes/DataTypeDateTime.h>
#include <Functions/IFunction.h>
#include <Core/DecimalFunctions.h>
#include <Functions/FunctionFactory.h>
#include <Core/Field.h>
#include <time.h>
namespace DB
{
namespace ErrorCodes
{
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
}
namespace
{
/// Get the UTC time. (It is a constant, it is evaluated once for the entire query.)
class ExecutableFunctionUTCTimestamp : public IExecutableFunction
{
public:
explicit ExecutableFunctionUTCTimestamp(time_t time_) : time_value(time_) {}
String getName() const override { return "UTCTimestamp"; }
ColumnPtr executeImpl(const ColumnsWithTypeAndName &, const DataTypePtr &, size_t input_rows_count) const override
{
return DataTypeDateTime().createColumnConst(
input_rows_count,
static_cast<UInt64>(time_value));
}
private:
time_t time_value;
};
class FunctionBaseUTCTimestamp : public IFunctionBase
{
public:
explicit FunctionBaseUTCTimestamp(time_t time_, DataTypes argument_types_, DataTypePtr return_type_)
: time_value(time_), argument_types(std::move(argument_types_)), return_type(std::move(return_type_)) {}
String getName() const override { return "UTCTimestamp"; }
const DataTypes & getArgumentTypes() const override
{
return argument_types;
}
const DataTypePtr & getResultType() const override
{
return return_type;
}
ExecutableFunctionPtr prepare(const ColumnsWithTypeAndName &) const override
{
return std::make_unique<ExecutableFunctionUTCTimestamp>(time_value);
}
bool isDeterministic() const override { return false; }
bool isDeterministicInScopeOfQuery() const override { return true; }
bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
private:
time_t time_value;
DataTypes argument_types;
DataTypePtr return_type;
};
class UTCTimestampOverloadResolver : public IFunctionOverloadResolver
{
public:
static constexpr auto name = "UTCTimestamp";
String getName() const override { return name; }
bool isDeterministic() const override { return false; }
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bool isVariadic() const override { return false; }
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size_t getNumberOfArguments() const override { return 0; }
static FunctionOverloadResolverPtr create(ContextPtr) { return std::make_unique<UTCTimestampOverloadResolver>(); }
DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
{
if (arguments.size() > 0)
{
throw Exception("Arguments size of function " + getName() + " should be 0", ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
}
return std::make_shared<DataTypeDateTime>();
}
FunctionBasePtr buildImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &) const override
{
if (arguments.size() > 0)
{
throw Exception("Arguments size of function " + getName() + " should be 0", ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
}
return std::make_unique<FunctionBaseUTCTimestamp>(time(nullptr), DataTypes(), std::make_shared<DataTypeDateTime>("UTC"));
}
};
}
/// UTC_timestamp for MySQL interface support
REGISTER_FUNCTION(UTCTimestamp)
{
factory.registerFunction<UTCTimestampOverloadResolver>({}, FunctionFactory::CaseInsensitive);
factory.registerAlias("UTC_timestamp", UTCTimestampOverloadResolver::name, FunctionFactory::CaseInsensitive);
}
}