Collation sequences: Use in comparison operations

By default, when QDB compares two text values, the comparison result is determined using memcmp(), regardless of the text encoding. QDB lets you write arbitrary comparison functions, known as user-defined collation routines, to use instead of memcmp().

QDB also features three built-in collation sequences:

Compare string data using memcmp(), regardless of text encoding. This is the default comparison method.
The same as BINARY, except that the 26 uppercase characters used by the English language are converted to their lowercase equivalents before the comparison is performed.
The same as BINARY, except that trailing spaces are ignored.

The last two sequences are intended for testing purposes.