ClickHouse/src/Functions/nowInBlock.cpp
Robert Schulze 72b9d75a84
Add compat setting for non-const timezones
SQL function toTimezone() converts a Date or DateTime into another
timezone. The problem is that the timezone is part of the Date /
DateTime type but not part of the internal representation (value). This
led to the fact that toTimeZone() wqith non-const timezones produced
wrong and misleading results until #48471 (shipped with v23.4) enforced
a const timezone.

Unfortunately, this PR also broke existing table definitions with
non-const timezones, e.g. in ALIAS expressions. So while #48471
addressed the issue appropriately, it is really backwards-incompatible.

This PR adds a setting to toggle the behavior and makes it also part of
the compatibility profile.
2023-06-10 16:56:42 +00:00

96 lines
2.7 KiB
C++

#include <Functions/IFunction.h>
#include <Functions/FunctionFactory.h>
#include <Functions/extractTimeZoneFromFunctionArguments.h>
#include <DataTypes/DataTypeDateTime.h>
#include <Columns/ColumnsDateTime.h>
#include <Columns/ColumnVector.h>
#include <Interpreters/Context.h>
namespace DB
{
namespace ErrorCodes
{
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
extern const int ILLEGAL_TYPE_OF_ARGUMENT;
}
namespace
{
/** Returns current time at calculation of every block.
* In contrast to 'now' function, it's not a constant expression and is not a subject of constant folding.
*/
class FunctionNowInBlock : public IFunction
{
public:
static constexpr auto name = "nowInBlock";
static FunctionPtr create(ContextPtr context)
{
return std::make_shared<FunctionNowInBlock>(context);
}
explicit FunctionNowInBlock(ContextPtr context)
: allow_nonconst_timezone_arguments(context->getSettings().allow_nonconst_timezone_arguments)
{}
String getName() const override
{
return name;
}
bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override
{
return false;
}
/// Optional timezone argument.
bool isVariadic() const override { return true; }
size_t getNumberOfArguments() const override { return 0; }
bool isDeterministic() const override
{
return false;
}
bool isDeterministicInScopeOfQuery() const override
{
return false;
}
DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
{
if (arguments.size() > 1)
{
throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH, "Arguments size of function {} should be 0 or 1", getName());
}
if (arguments.size() == 1 && !isStringOrFixedString(arguments[0].type))
{
throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Arguments of function {} should be String or FixedString",
getName());
}
if (arguments.size() == 1)
{
return std::make_shared<DataTypeDateTime>(extractTimeZoneNameFromFunctionArguments(arguments, 0, 0, allow_nonconst_timezone_arguments));
}
return std::make_shared<DataTypeDateTime>();
}
ColumnPtr executeImpl(const ColumnsWithTypeAndName &, const DataTypePtr &, size_t input_rows_count) const override
{
return ColumnDateTime::create(input_rows_count, static_cast<UInt32>(time(nullptr)));
}
private:
const bool allow_nonconst_timezone_arguments;
};
}
REGISTER_FUNCTION(NowInBlock)
{
factory.registerFunction<FunctionNowInBlock>();
}
}