Thread: How to get the OID of a view
I am trying to write a query to return the names, and data types of all the
columns in a view. It has been pointed out to me that the best approach
would be using pg_catalog. OK, so I found pg_view, which I can get the names
of a the views from and pg_attribute which can give me the column names,
but it looks like i need to join this on OID, and pg_table does not have
that data.
--
"They that would give up essential liberty for temporary safety deserve
neither liberty nor safety."
-- Benjamin Franklin
stan <stanb@panix.com> writes:
> I am trying to write a query to return the names, and data types of all the
> columns in a view. It has been pointed out to me that the best approach
> would be using pg_catalog. OK, so I found pg_view, which I can get the names
> of a the views from and pg_attribute which can give me the column names,
> but it looks like i need to join this on OID, and pg_table does not have
> that data.
Yeah, pg_tables is just a user-friendly view, it's not really that
useful for programmatic work. I'd look directly at pg_class and
pg_attribute for this problem.
A good way to learn what to do is to see what psql does for its
various \d commands --- if you start it with the -E option you'll
see the underlying SQL it issues. It'll likely be more complicated
than you want, but you can strip away what's not useful for you.
regards, tom lane
Hello
--------------
I am trying to write a query to return the names, and data types of all the
columns in a view. It has been pointed out to me that the best approach
would be using pg_catalog. OK, so I found pg_view, which I can get the names
of a the views from and pg_attribute which can give me the column names,
but it looks like i need to join this on OID, and pg_table does not have
that data.
--
"They that would give up essential liberty for temporary safety deserve
neither liberty nor safety."
-- Benjamin Franklin
You find the oid of the views in pg_catalog.pg_class (relkind 'v').
Regards
Charles
On 5/22/20 9:15 AM, stan wrote:
> I am trying to write a query to return the names, and data types of all the
> columns in a view. It has been pointed out to me that the best approach
> would be using pg_catalog. OK, so I found pg_view, which I can get the names
> of a the views from and pg_attribute which can give me the column names,
> but it looks like i need to join this on OID, and pg_table does not have
> that data.
>
>
I'm guessing you mean pg_tables.
In any case, go straight to the source pg_class:
\dv
List of relations
Schema | Name | Type | Owner
--------+------------------+------+----------
public | tag_litem | view | postgres
public | tag_short_status | view | postgres
select oid, relname, relkind from pg_class where relname = 'tag_litem';
oid | relname | relkind
-------+-----------+---------
60558 | tag_litem | v
Where relkind = 'v' means view:
https://www.postgresql.org/docs/12/catalog-pg-class.html
--
Adrian Klaver
adrian.klaver@aklaver.com
On Fri, May 22, 2020 at 9:15 AM stan <stanb@panix.com> wrote:
I am trying to write a query to return the names, and data types of all the
columns in a view. It has been pointed out to me that the best approach
would be using pg_catalog. OK, so I found pg_view, which I can get the names
of a the views from and pg_attribute which can give me the column names,
but it looks like i need to join this on OID, and pg_table does not have
that data.
The table you want is pg_class:
If the system views listed in [1] don't provide you what you need you need to fall-back to the system tables listed in [2].
David J.