Обсуждение: how can I find out the numeric directory name of each database in PostgreSQL 8.3

Hi,

In PostgreSQL 7.x, I can use SQL:
select datname, oid from pg_database
to find out the numeric directory name under $PGDATA/base for each
database. But it doesn't work for PostgreSQL 8.3.
Is there any way I can do it for 8.3?

Thanks,
--
Justin Yao

Hi,

Justin Yao wrote:
> Hi,
>
> In PostgreSQL 7.x, I can use SQL:
> select datname, oid from pg_database
> to find out the numeric directory name under $PGDATA/base for each
> database. But it doesn't work for PostgreSQL 8.3.
> Is there any way I can do it for 8.3?

What would you do with that name once you have it?

Tino

nothing special, just curious about it.
I suppose it should be able to be located by SQL.

Justin

Tino Wildenhain wrote:
> Hi,
>
> Justin Yao wrote:
>> Hi,
>>
>> In PostgreSQL 7.x, I can use SQL:
>> select datname, oid from pg_database
>> to find out the numeric directory name under $PGDATA/base for each
>> database. But it doesn't work for PostgreSQL 8.3.
>> Is there any way I can do it for 8.3?
>
> What would you do with that name once you have it?
>
> Tino

Justin Yao <justin@snooth.com> writes:
> In PostgreSQL 7.x, I can use SQL:
> select datname, oid from pg_database
> to find out the numeric directory name under $PGDATA/base for each
> database. But it doesn't work for PostgreSQL 8.3.

It works for me ... what problem are you having?

            regards, tom lane

forget it..... I am really sorry about that.
it works for me, too.

when I did :

dbname=> \d pg_database
     Table "pg_catalog.pg_database"
     Column     |   Type    | Modifiers
---------------+-----------+-----------
  datname       | name      | not null
  datdba        | oid       | not null
  encoding      | integer   | not null
  datistemplate | boolean   | not null
  datallowconn  | boolean   | not null
  datconnlimit  | integer   | not null
  datlastsysoid | oid       | not null
  datfrozenxid  | xid       | not null
  dattablespace | oid       | not null
  datconfig     | text[]    |
  datacl        | aclitem[] |
Indexes:
     "pg_database_datname_index" UNIQUE, btree (datname), tablespace
"pg_global"
     "pg_database_oid_index" UNIQUE, btree (oid), tablespace "pg_global"
Triggers:
     pg_sync_pg_database AFTER INSERT OR DELETE OR UPDATE ON pg_database
FOR EACH STATEMENT EXECUTE PROCEDURE flatfile_update_trigger()
Tablespace: "pg_global"

I didn't find the Column "oid", I take granted to think it may not work,
but I didn't issue a command to have a try.

Really sorry about that.

But the question is, why there's no column named "oid" and it still works?

Thanks,
Justin


Tom Lane wrote:
> Justin Yao <justin@snooth.com> writes:
>> In PostgreSQL 7.x, I can use SQL:
>> select datname, oid from pg_database
>> to find out the numeric directory name under $PGDATA/base for each
>> database. But it doesn't work for PostgreSQL 8.3.
>
> It works for me ... what problem are you having?
>
>             regards, tom lane
>

Justin Yao <justin@snooth.com> writes:
> But the question is, why there's no column named "oid" and it still works?

\d doesn't show system columns.
http://www.postgresql.org/docs/8.3/static/ddl-system-columns.html

            regards, tom lane

thanks so much!

Tom Lane wrote:
> Justin Yao <justin@snooth.com> writes:
>> But the question is, why there's no column named "oid" and it still works?
>
> \d doesn't show system columns.
> http://www.postgresql.org/docs/8.3/static/ddl-system-columns.html
>
>             regards, tom lane
>