restore backup : erreur

Hello,

suite à un excellent cours chez Dalibo , je fais des tests de backup
restore .(pg_dump--pg_restore)

export 8.4 -- import 9.1.3

j'obtiens ce message:
postgres(at)ubuntu:/u00/app/postgresql/admin/prod913/dump$ pg_restore -d cave
-U caviste cave.tar
Password:
pg_restore: [archiver (db)] Error while PROCESSING TOC:
pg_restore: [archiver (db)] Error from TOC entry 484; 2612 16386 PROCEDURAL
LANGUAGE plpgsql postgres
pg_restore: [archiver (db)] could not execute query: ERROR: language
"plpgsql" already exists
Command was: CREATE PROCEDURAL LANGUAGE plpgsql;

pg_restore: WARNING: no privileges could be revoked for "public"
pg_restore: WARNING: no privileges could be revoked for "public"
pg_restore: WARNING: no privileges were granted for "public"
pg_restore: WARNING: no privileges were granted for "public"
WARNING: errors ignored on restore: 1

Comme si le language avait déja été chargé. hors je n'ai pas chargé aprés
le creatdb ???

A+
Pierre
Pierre Boizot

G+ <https://plus.google.com/u/0/107377830070954284209/about>