How to recreate index of a pg table

Hi,

When I make a vacuum on my data base, I have the following NOTICE:

NOTICE: Index pg_attrdef_adrelid_index: NUMBER OF INDEX' TUPLES (36) IS
NOT THE SAME AS HEAP' (34).
Recreate the index.
NOTICE: Index pg_attrdef_adrelid_index: NUMBER OF INDEX' TUPLES (36) IS
NOT THE SAME AS HEAP' (34).
Recreate the index.

I had the same trouble on my own talbe, and to recreate the index, I
drop the index and recreate it.

But with an pg table I have the following message when I try to drop the
index :

ERROR: class "pg_attrdef_adrelid_index" is a system catalog index

How can I recreate my pg_attrdef_adrelid_index?

Thanks.

Best regards, Jérome Knobl, Lausanne, Switzerland