Re: Primary key data type: integer vs identity

On 4/19/19 1:02 PM, Ken Tanzer wrote:
> On Fri, Apr 19, 2019 at 12:50 PM Adrian Klaver
> <adrian(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)com>> wrote:
>
> On 4/19/19 12:35 PM, Ken Tanzer wrote:
>
> >
> > Thanks Adrian.  You are as usual correct.  (I had a bunch of tables
> > created by a function that I assumed were serial, but were not.)
> > Identity columns still seem tidier and more manageable.  Can you
> tell if
> > the function I referenced would change the ownership or not?
>
> I believe in 'when it doubt try it, whats the worst that can happen?:)':
>
>
> I agree, and if I had a copy of 10+ running, I probably would have! :)
>
> <NOTE> I needed to be a superuser to run due to this:
> ERROR:  permission denied for table pg_depend
> CONTEXT:  SQL statement "UPDATE pg_depend
>      SET deptype = 'i'
>      WHERE (classid, objid, objsubid) = ('pg_class'::regclass,
> seqid, 0)
>        AND deptype = 'a'"
> PL/pgSQL function upgrade_serial_to_identity(regclass,name) line 31 at
> SQL statement
>
>
> test=# create table serial_test(id serial, fld_1 text);
> CREATE TABLE
> test=# \dp serial_test
>                                  Access privileges
>   Schema |    Name     | Type  | Access privileges | Column
> privileges |
> Policies
> --------+-------------+-------+-------------------+-------------------+----------
>   public | serial_test | table |                   |
>    |
> (1 row)
>
> test=# select upgrade_serial_to_identity('serial_test', 'id');
>   upgrade_serial_to_identity
> ----------------------------
>
> (1 row)
>
> test=# \d serial_test
>                           Table "public.serial_test"
>   Column |  Type   | Collation | Nullable |             Default
>
> --------+---------+-----------+----------+----------------------------------
>   id     | integer |           | not null | generated by default as
> identity
>   fld_1  | text    |           |          |
>
>
> test=# \dp+ serial_test
>                                  Access privileges
>   Schema |    Name     | Type  | Access privileges | Column
> privileges |
> Policies
> --------+-------------+-------+-------------------+-------------------+----------
>   public | serial_test | table |                   |
>    |
> (1 row)
>
>
> Maybe I'm missing it, but I'm not really sure what that is supposed to
> be telling me about the ownership of the sequence.
>
> The scenario I'm wondering about is:
>
> Table A owned by User 1, and has column created as serial
> The created sequence is altered to be owned by User 2 (with User 1
> granted select & update)
> upgrade_serial_to_identity applied to Table A
> At that point, who owns the sequence?
>
> I can wait until I've got 10+ running and try it myself, but I thought
> maybe someone would know the answer and be willing to share.

select version();
version

----------------------------------------------------------------------------------------------------------------------------
PostgreSQL 11.2 on x86_64-pc-linux-gnu, compiled by gcc (SUSE Linux)
7.3.1 20180323 [gcc-7-branch revision 258812], 64-bit

select session_user, current_user;
session_user | current_user
--------------+--------------
aklaver | aklaver

create table serial_test(id serial, fld_1 text);
CREATE TABLE

\d

List of relations
Schema | Name | Type | Owner
--------+--------------------+----------+----------

public | serial_test | table | aklaver
public | serial_test_id_seq | sequence | aklaver

test_(aklaver)> \c - postgres
You are now connected to database "test" as user "postgres".
test_(postgres)# select session_user, current_user;
session_user | current_user
--------------+--------------
postgres | postgres
(1 row)

test_(postgres)# select upgrade_serial_to_identity('serial_test', 'id');
upgrade_serial_to_identity
----------------------------

(1 row)

List of relations
Schema | Name | Type | Owner
--------+--------------------+----------+----------

public | serial_test | table | aklaver
public | serial_test_id_seq | sequence | aklaver

The function is working directly on the system catalogs and I do not
anything that changes ownership:

UPDATE pg_depend
SET deptype = 'i'
WHERE (classid, objid, objsubid) = ('pg_class'::regclass, seqid, 0)
AND deptype = 'a';

-- mark the column as identity column
UPDATE pg_attribute
SET attidentity = 'd'
WHERE attrelid = tbl
AND attname = col;

>
> Thanks!

>
> Ken
>
>
> --
> AGENCY Software
> A Free Software data system
> By and for non-profits
> /http://agency-software.org//
> /https://demo.agency-software.org/client/
> ken(dot)tanzer(at)agency-software(dot)org <mailto:ken(dot)tanzer(at)agency-software(dot)org>
> (253) 245-3801
>
> Subscribe to the mailing list
> <mailto:agency-general-request(at)lists(dot)sourceforge(dot)net?body=subscribe> to
> learn more about AGENCY or
> follow the discussion.

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com