From: Jade Lovelace
I have intentionally been careful to not guarantee that the
automatically generated name *is* what's documented, but instead give
the general idea.
Knowing the format is useful for people writing migrations/ORM tools
which need to name their unique indices and may wish to use
Previously, the automatically generated names were entirely undocumented. That
is not a very good state of affairs: although it's possibly inconvenient to
rigidly specify what it is since it's an implementation detail, these names are
user-visible, and it would be good to have documentation at all.
