[GENERAL] Issue dumping schema using readonly user

[Daniel LaMotte]

Here’s the situation:

    % psql --version
    psql (PostgreSQL) 9.3.5
    % postgres --version
    postgres (PostgreSQL) 9.3.5
    % psql mydatabase
    create table mytable_is_readonly (id uuid primary key, text text not null);
    create table mytable_is_not_readonly (id uuid primary key, text
text not null);
    create user readonly with password 'readonly';
    grant select on mytable_is_readonly to readonly;

    % psql mydatabase readonly
    \d mytable_is_readonly
                             Table "public.mytable_is_readonly"
     Column │  Type   │                            Modifiers
    
────────┼─────────┼──────────────────────────────────────────────────────────────────
     id     │ integer │ not null default
nextval('mytable_is_readonly_id_seq'::regclass)
     text   │ text    │ not null
    Indexes:
        "mytable_is_readonly_pkey" PRIMARY KEY, btree (id)

    \d mytable_is_not_readonly
                             Table "public.mytable_is_not_readonly"
     Column │  Type   │                              Modifiers
    
────────┼─────────┼──────────────────────────────────────────────────────────────────────
     id     │ integer │ not null default
nextval('mytable_is_not_readonly_id_seq'::regclass)
     text   │ text    │ not null
    Indexes:
        "mytable_is_not_readonly_pkey" PRIMARY KEY, btree (id)

    % pg_dump -U readonly mydatabase --schema-only --table=mytable_is_readonly
    ... this outputs and works

    % pg_dump -U readonly mydatabase --schema-only
--table=mytable_is_not_readonly
    pg_dump: [archiver (db)] query failed: ERROR:  permission denied
for relation mytable_is_not_readonly
    pg_dump: [archiver (db)] query was: LOCK TABLE
public.mytable_is_not_readonly IN ACCESS SHARE MODE

Is this a bug? Or defined behavior that is expected? My use case is that I
have some tables that I don’t want to allow the readonly account to access
data in but want to allow it to see the schema of that table. My guess was
that since it could see the schema interactively in psql, that it should be
allowed to pg_dump the table with schema only no problem.

Thanks for the help!

- Dan
​