Function CVT2_get_binary_comparable_desc

src/jrd/cvt2.cpp:138–203

bool CVT2_get_binary_comparable_desc(dsc* result, const dsc* arg1, const dsc* arg2)
{
/**************************************
 *
 *	C V T 2 _ g e t _ b i n a r y _ c o m p a r a b l e _ d e s c
 *
 **************************************
 *
 * Functional description
 *	Return descriptor of the data type to be used for direct (binary) comparison of the given arguments.
 *
 **************************************/

	if (arg1->dsc_dtype == dtype_blob || arg2->dsc_dtype == dtype_blob ||
		arg1->dsc_dtype == dtype_array || arg2->dsc_dtype == dtype_array)
	{
		// Any of the arguments is a blob or an array
		return false;
	}

	if (arg1->dsc_dtype == dtype_dbkey || arg2->dsc_dtype == dtype_dbkey)
	{
		// Any of the arguments is DBKEY
		result->makeText(MAX(arg1->getStringLength(), arg2->getStringLength()), ttype_binary);
	}
	else if (arg1->isText() && arg2->isText())
	{
		// Both arguments are strings
		if (arg1->getTextType() != arg2->getTextType())
		{
			// Charsets/collations are different
			return false;
		}

		if (arg1->dsc_dtype == arg2->dsc_dtype)
		{
			*result = *arg1;
			result->dsc_length = MAX(arg1->dsc_length, arg2->dsc_length);
		}
		else
		{
			result->makeText(MAX(arg1->getStringLength(), arg2->getStringLength()),
				arg1->getTextType());
		}
	}
	else if (arg1->dsc_dtype == arg2->dsc_dtype && arg1->dsc_scale == arg2->dsc_scale)
	{
		// Arguments can be compared directly
		*result = *arg1;
	}
	else if (arg1->dsc_dtype == dtype_boolean || arg2->dsc_dtype == dtype_boolean)
	{
		// boolean is not comparable to a non-boolean
		return false;
	}
	else
	{
		// Arguments are of different data types