Hola Ana
Fijate esto
http://informix-technology.blogspot.com/2006/10/when-exclusive-is-not-really-exclusive.html
la solucion que propone es
SET LOCK MODE TO WAIT;
BEGIN WORK;
LOCK TABLE IN EXCLUSIVE MODE;
– dummy grant to prevent new sessions from getting holds on the table structure
GRANT SELECT ON FOR dummy_user;
– before continuing use onstat -g opn to identify the sessions with references
– and kill them…
ALTER TABLE ;
– clean up the dummy GRANT
REVOKE SELECT ON FROM dummy_user;
COMMIT WORK;
fijate si funciona
Emilio