The file name databases contain lists of files that were in particular
directory trees when the databases were last updated. The file name
database format changed starting with GNU locate version 4.0 to
allow machines with different byte orderings to share the databases. The
new GNU locate can read both the old and new database formats.
However, old versions of locate and find produce incorrect
results if given a new-format database.
If you run locate --statistics, the resulting summary indicates the type of each locate database.