Restore after using pg_dumpall

[Asmus Reinhard <Reinhard.Asmus@xxxxxxxxxxxxxx>]

Hallo,

 

between

 

pg_dumpall > alldb.sql (store)

 

and

 

psql –f alldb.sql postgres (restore)

 

is it necessary to drop existing objects (for example roles, …) ?

 

Any help is appreciated.