TalkingQuickly's Today I Learned

Who has access to which schemas in Postgres

Great little snippet for understanding which users have which privileges on a schema in Postgres / Redshift.

SELECT *
FROM
    (
    SELECT
        schemaname
        ,objectname
        ,usename
        ,HAS_TABLE_PRIVILEGE(usrs.usename, fullobj, 'select') AND has_schema_privilege(usrs.usename, schemaname, 'usage')  AS sel
        ,HAS_TABLE_PRIVILEGE(usrs.usename, fullobj, 'insert') AND has_schema_privilege(usrs.usename, schemaname, 'usage')  AS ins
        ,HAS_TABLE_PRIVILEGE(usrs.usename, fullobj, 'update') AND has_schema_privilege(usrs.usename, schemaname, 'usage')  AS upd
        ,HAS_TABLE_PRIVILEGE(usrs.usename, fullobj, 'delete') AND has_schema_privilege(usrs.usename, schemaname, 'usage')  AS del
        ,HAS_TABLE_PRIVILEGE(usrs.usename, fullobj, 'references') AND has_schema_privilege(usrs.usename, schemaname, 'usage')  AS ref
    FROM
        (
        SELECT schemaname, 't' AS obj_type, tablename AS objectname, schemaname + '.' + tablename AS fullobj FROM pg_tables
        WHERE schemaname not in ('pg_internal')
        UNION
        SELECT schemaname, 'v' AS obj_type, viewname AS objectname, schemaname + '.' + viewname AS fullobj FROM pg_views
        WHERE schemaname not in ('pg_internal')
        ) AS objs
        ,(SELECT * FROM pg_user) AS usrs
    ORDER BY fullobj
    )
WHERE (sel = true or ins = true or upd = true or del = true or ref = true)
and schemaname='SOME_SCHEMA_NNAME';

Note that if you can't track down why a user has a particular permission, it's worth delving into the permissions granted to the public role, more about that here: https://blog.dbrhino.com/locking-down-permissions-in-postgresql-and-redshift.html