**Use case**

Workload generation with continuous queries.

**Describe the solution you'd like**

Similar to now() but non-constant.

registerFunctionAddSeconds(factory);
    registerFunctionAddMinutes(factory);
    registerFunctionAddHours(factory);
    registerFunctionAddDays(factory);
    registerFunctionAddWeeks(factory);
    registerFunctionAddMonths(factory);
    registerFunctionAddQuarters(factory);
    registerFunctionAddYears(factory);
    registerFunctionSubtractNanoseconds(factory);
    registerFunctionSubtractMicroseconds(factory);
    registerFunctionSubtractMilliseconds(factory);
    registerFunctionSubtractSeconds(factory);
    registerFunctionSubtractMinutes(factory);
    registerFunctionSubtractHours(factory);
    registerFunctionSubtractDays(factory);
    registerFunctionSubtractWeeks(factory);
    registerFunctionSubtractMonths(factory);
    registerFunctionSubtractQuarters(factory);
    registerFunctionSubtractYears(factory);
    registerFunctionDateDiff(factory);
    registerFunctionDateName(factory);
    registerFunctionMonthName(factory);
    registerFunctionToTimeZone(factory);
    registerFunctionFormatDateTime(factory);
    registerFunctionFromModifiedJulianDay(factory);
    registerFunctionDateTrunc(factory);
    registerFunctiontimezoneOffset(factory);
}
}