Within the database, filenames are terminated with a null character. This is the case for both the old and the new format.
When the new database format is being used, the compression technique
used to generate the database though relies on the ability to sort the
list of files before they are presented to frcode.
If the system's sort command allows its input list of files to be
separated with null characters via the -z option, this option
is used and therefore updatedb and locate will both
correctly handle filenames containing newlines. If the sort
command lacks support for this, the list of files is delimited with
the newline character, meaning that parts of filenames containing
newlines will be incorrectly sorted. This can result in both
incorrect matches and incorrect failures to match.
On the other hand, if you are using the old database format, filenames
with embedded newlines are not correctly handled. There is no
technical limitation which enforces this, it's just that the
bigram program has no been updated to support lists of
filenames separated by nulls.
So, if you are using the new database format (this is the default) and
your system uses GNU find, newlines will be correctly handled
at all times. Otherwise, newlines may not be correctly handled.