[Auth] "ident" method and LDAP user accounts

I manage a Debian/Linux machine which runs PostgreSQL 7.4.7.

All the user accounts, including mine, are in a LDAP database. Thanks
to NSS (Name Service Switch) all applications have access to the LDAP
accounts (getpwuid(3) and getpwnam(3) use LDAP). But not PostgreSQL.

When I connect locally (Linux as SO_PEERCRED so the ident daemon is
not used) with the "ident" method, I get rejected.

If I create an ident map to map the numeric UID to my name, it works:

# MAPNAME     IDENT-USERNAME    PG-USERNAME
ldapuser      1000              bortzmeyer

It is of course very inconvenient to duplicate my LDAP database into
pg_ident.conf. Is there a better way?