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Thread: Table containing only valid table names

Table containing only valid table names

From
Michael Graham
Date:
Hi all,

I'm trying to create a table that contains only valid table names.  I'm
currently using reglass for the field type which works fine for when you
are adding to the table (i.e. you can't add invalid tablesnames to the
table).  But it is still possible to leave the table in an invalid state
after doing a drop table.

So for example:

=> CREATE TABLE table_list (tablename regclass);
CREATE TABLE
=> INSERT INTO table_list VALUES ('foo');
ERROR:  relation "foo" does not exist
LINE 1: INSERT INTO table_list VALUES ('foo');
                                        ^
=> CREATE TABLE foo (a int);
CREATE TABLE
=> INSERT INTO table_list VALUES ('foo');
INSERT 0 1
=> DROP TABLE foo;
DROP TABLE
=> SELECT * FROM table_list;
  tablename
-----------
  122860
(1 row)

Does any one have any ideas that could be used to stop this from
happening?  I'm not really in the position to have different users for
the modification of the table_list and the drops so I don't think I can
use different roles.

I'm pretty sure I can't do what I need as postgres doesn't support
triggers on DDL but maybe I'm wrong.

Cheers,
--
Michael Graham

Re: Table containing only valid table names

From
Richard Huxton
Date:
On 26/04/13 16:09, Michael Graham wrote:
> I'm pretty sure I can't do what I need as postgres doesn't support
> triggers on DDL but maybe I'm wrong.

If you're still in development and not live, it'll be worth checking out 9.3

http://www.postgresql.org/docs/devel/static/event-triggers.html


--
   Richard Huxton
   Archonet Ltd

Re: Table containing only valid table names

From
salah jubeh
Date:
Hello,

You can have the list of table names  from pg_class  such as

SELECT c.relname as "Name" ,
FROM pg_catalog.pg_class c
LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE c.relkind IN ('r') AND n.nspname NOT IN  ('pg_toast', 'pg_catalog', 'information_schema') ;

So, if you want to store all table names you can just create a view around the  above query.

Also , the following is not a perfect solution;  but I think it will work.  You can join your table with pg_class to filter out tables which are Dropped

Regards

From: Richard Huxton <dev@archonet.com>
To: Michael Graham <mgraham@bloxx.com>
Cc: "pgsql-general@postgresql.org" <pgsql-general@postgresql.org>
Sent: Friday, April 26, 2013 5:21 PM
Subject: Re: [GENERAL] Table containing only valid table names

On 26/04/13 16:09, Michael Graham wrote:
> I'm pretty sure I can't do what I need as postgres doesn't support
> triggers on DDL but maybe I'm wrong.

If you're still in development and not live, it'll be worth checking out 9.3

http://www.postgresql.org/docs/devel/static/event-triggers.html


--
  Richard Huxton
  Archonet Ltd


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Re: Table containing only valid table names

From
Jasen Betts
Date:
On 2013-04-26, Michael Graham <mgraham@bloxx.com> wrote:
> Hi all,
>
> I'm trying to create a table that contains only valid table names.

could you get by with a view off pg_catalog.pg_tables or
information_schema.tables

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