Tested against PostgreSQL version 9.6 and 9.5
On any database, when the pg_database access is restraint for standard users:
psql> REVOKE ALL ON pg_database FROM public;
it not possible anymore to query the field character_octet_length from the view information_schema.columns:
psql> SELECT character_octet_length FROM information_schema.columns;
ERROR: permission denied for relation pg_database
CONTEXT: SQL function "_pg_char_octet_length" statement 1
The same problem can be found in information_schema.domains.
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