pg_locks documentation vs. SSI

While taking a look at the existing documentation for pg_locks I came
across the following paragraph:

<para>
When the <structname>pg_locks</structname> view is accessed, the
internal lock manager data structures are momentarily locked, and
a copy is made for the view to display. This ensures that the
view produces a consistent set of results, while not blocking
normal lock manager operations longer than necessary. Nonetheless
there could be some impact on database performance if this view is
frequently accessed.
</para>

AFAICS, this is no longer quite true. The view of the data from the
main lock manager will be self-consistent, and the view of the data
from the predicate lock manager will be self-consistent, but they need
not be consistent with each other. I don't think that's a problem we
need to fix, but we probably ought to make the documentation match the
behavior.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company