Documentation should specify supported PostgreSQL versions (i.e. 9.5+)

[pdecat]

The current PostgreSQL terraform provider depends on features only available with PostgreSQL versions 9.5+ such as row-level security.

This should be specified in the provider's documentation as it is not compatible with 9.4.x and earlier versions of PostgreSQL.

https://www.postgresql.org/docs/9.5/static/ddl-rowsecurity.html
https://wiki.postgresql.org/wiki/Row-security
https://www.postgresql.org/docs/9.5/static/release-9-5.html#AEN128103

Specifically, the code refers to the rolbypassrls column which does not exist on 9.4.x and earlier versions of PostgreSQL:

	var roleSuperuser, roleInherit, roleCreateRole, roleCreateDB, roleCanLogin, roleReplication, roleBypassRLS bool
	var roleConnLimit int
	var roleName, roleValidUntil string
	err = conn.QueryRow("SELECT rolname, rolsuper, rolinherit, rolcreaterole, rolcreatedb, rolcanlogin, rolreplication, rolconnlimit, COALESCE(rolvaliduntil::TEXT, 'infinity'), rolbypassrls FROM pg_catalog.pg_roles WHERE rolname=$1", roleId).Scan(&roleName, &roleSuperuser, &roleInherit, &roleCreateRole, &roleCreateDB, &roleCanLogin, &roleReplication, &roleConnLimit, &roleValidUntil, &roleBypassRLS)

cf. https://github.com/terraform-providers/terraform-provider-postgresql/blob/v0.1.0/postgresql/resource_postgresql_role.go#L345

Trying to query this column fails on PostgreSQL 9.4.9:

# psql -h myhost -U myuser -d mydb
psql (9.6.1, server 9.4.9)
SSL connection (protocol: TLSv1.2, cipher: ECDHE-RSA-AES256-GCM-SHA384, bits: 256, compression: off)
Type "help" for help.

mydb=> SELECT rolname, rolsuper, rolinherit, rolcreaterole, rolcreatedb, rolcanlogin, rolreplication, rolconnlimit, COALESCE(rolvaliduntil::TEXT, 'infinity'), rolbypassrls FROM pg_catalog.pg_roles WHERE rolname='mr_readonly';
ERROR:  column "rolbypassrls" does not exist
LINE 1: ...limit, COALESCE(rolvaliduntil::TEXT, 'infinity'), rolbypassr...
                                                             ^
mydb=> SELECT rolname, rolsuper, rolinherit, rolcreaterole, rolcreatedb, rolcanlogin, rolreplication, rolconnlimit, COALESCE(rolvaliduntil::TEXT, 'infinity') FROM pg_catalog.pg_roles WHERE rolname='mr_readonly';
   rolname   | rolsuper | rolinherit | rolcreaterole | rolcreatedb | rolcanlogin | rolreplication | rolconnlimit | coalesce
-------------+----------+------------+---------------+-------------+-------------+----------------+--------------+----------
 mr_readonly | f        | t          | f             | f           | f           | f              |           -1 | infinity
(1 row)

oc=>

[sean-]

@pdecat, as soon as #12 lands you'll be in a good spot. This has been a nagging issue for a while.