pg.ddx.io pgsql-sql@postgresql.org mailing list archive
help / color / mirror / Atom feedRelated tables to a view
6+ messages / 4 participants
[nested] [flat]
* Related tables to a view
@ 2006-12-25 21:52 Jan Meyland Andersen <jma@agile.dk>
2006-12-26 04:10 ` Re: Related tables to a view Michael Fuhr <mike@fuhr.org>
0 siblings, 1 reply; 6+ messages in thread
From: Jan Meyland Andersen @ 2006-12-25 21:52 UTC (permalink / raw)
To: pgsql-sql
Hi
I need a function which are able to return the underlying tables to a view.
If I have a view which is a selection from field1 and field2 from table1
and field1 and field2 from table2.
How can I make a selection which returns the relation for the fields in a
way so I am able to se which field belongs to which table.
SELECT * FROM pg_views WHERE viewname='TestView' will return the schema
and the definition for me.
SELECT * FROM pg_class WHERE relname = 'TestView' will return some oids etc.
SELECT * FROM pg_attribute JOIN pg_class ON attrelid = pg_class.oid AND
pg_class.relname='TestView' will return the fields including oids etc.
But I just cant find out how to find the tables for each field.
I hope someone are able to help me with this problem.
Regards
Jan Andersen
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Related tables to a view
2006-12-25 21:52 Related tables to a view Jan Meyland Andersen <jma@agile.dk>
@ 2006-12-26 04:10 ` Michael Fuhr <mike@fuhr.org>
2006-12-26 10:54 ` Re: Related tables to a view Jan Andersen <jma@agile.dk>
2006-12-26 20:10 ` Re: Related tables to a view Jan Meyland Andersen <jma@agile.dk>
0 siblings, 2 replies; 6+ messages in thread
From: Michael Fuhr @ 2006-12-26 04:10 UTC (permalink / raw)
To: Jan Meyland Andersen <jma@agile.dk>; +Cc: pgsql-sql
On Mon, Dec 25, 2006 at 10:52:03PM +0100, Jan Meyland Andersen wrote:
> If I have a view which is a selection from field1 and field2 from table1
> and field1 and field2 from table2.
>
> How can I make a selection which returns the relation for the fields in a
> way so I am able to se which field belongs to which table.
You could query pg_depend to find out which tables and columns the
view's rewrite rule depends on but that's not as specific as what
you're requesting. I'm not aware of a way to associate a particular
table column with a particular view column short of parsing the view
definition or rule action; doing so would have to allow for the
possibility of a view column deriving its value from an arbitrarily
complex expression involving multiple tables, subqueries, etc.
--
Michael Fuhr
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Related tables to a view
2006-12-25 21:52 Related tables to a view Jan Meyland Andersen <jma@agile.dk>
2006-12-26 04:10 ` Re: Related tables to a view Michael Fuhr <mike@fuhr.org>
@ 2006-12-26 10:54 ` Jan Andersen <jma@agile.dk>
1 sibling, 0 replies; 6+ messages in thread
From: Jan Andersen @ 2006-12-26 10:54 UTC (permalink / raw)
To: pgsql-sql
> You could query pg_depend to find out which tables and columns the
> view's rewrite rule depends on but that's not as specific as what
> you're requesting. I'm not aware of a way to associate a particular
> table column with a particular view column short of parsing the view
> definition or rule action; doing so would have to allow for the
> possibility of a view column deriving its value from an arbitrarily
> complex expression involving multiple tables, subqueries, etc.
Yes I'm aware of the "problem" about arbitrary or scalar values but this is
not a problem in this specific case. If a field or value do not have a table
reference then it is not needed in the resultset. I only need those values
which have a direct connection to a table.
Is the only possible way then to analyse the description field in pg_view?
I was hoping for a more simple way to get the needed result.
Regards
Jan Andersen
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Related tables to a view
2006-12-25 21:52 Related tables to a view Jan Meyland Andersen <jma@agile.dk>
2006-12-26 04:10 ` Re: Related tables to a view Michael Fuhr <mike@fuhr.org>
@ 2006-12-26 20:10 ` Jan Meyland Andersen <jma@agile.dk>
2006-12-26 20:27 ` Re: Related tables to a view Jim Buttafuoco <jim@contactbda.com>
1 sibling, 1 reply; 6+ messages in thread
From: Jan Meyland Andersen @ 2006-12-26 20:10 UTC (permalink / raw)
To: Michael Fuhr <mike@fuhr.org>; +Cc: Jan Meyland Andersen <jma@agile.dk>; pgsql-sql
> You could query pg_depend to find out which tables and columns the
> view's rewrite rule depends on but that's not as specific as what
> you're requesting. I'm not aware of a way to associate a particular
> table column with a particular view column short of parsing the view
> definition or rule action; doing so would have to allow for the
> possibility of a view column deriving its value from an arbitrarily
> complex expression involving multiple tables, subqueries, etc.
I have been thinking the problem through again, and I think I am able to
solve the problem if I just know which tables the view is using.
But how do I get this information from the pg_depend table?
Regards
Jan
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Related tables to a view
2006-12-25 21:52 Related tables to a view Jan Meyland Andersen <jma@agile.dk>
2006-12-26 04:10 ` Re: Related tables to a view Michael Fuhr <mike@fuhr.org>
2006-12-26 20:10 ` Re: Related tables to a view Jan Meyland Andersen <jma@agile.dk>
@ 2006-12-26 20:27 ` Jim Buttafuoco <jim@contactbda.com>
2006-12-27 15:58 ` Re: Related tables to a view Jan Meyland Andersen <jma@agile.dk>
0 siblings, 1 reply; 6+ messages in thread
From: Jim Buttafuoco @ 2006-12-26 20:27 UTC (permalink / raw)
To: 'Jan Meyland Andersen' <jma@agile.dk>; 'Michael Fuhr' <mike@fuhr.org>; +Cc: pgsql-sql
Try this query
select a.relname as base,a.relkind
from
pg_class a
join pg_depend d on (a.oid = d.refobjid)
join pg_class c on (d.classid = c.oid)
join pg_rewrite r on (objid = r.oid)
join pg_class v on (ev_class = v.oid)
where a.relkind in('r', 'v')
and a.relname <> v.relname
and v.relname='YOUR VIEW NAME HERE'
order by 1
-----Original Message-----
From: pgsql-sql-owner@postgresql.org [mailto:pgsql-sql-owner@postgresql.org]
On Behalf Of Jan Meyland Andersen
Sent: Tuesday, December 26, 2006 3:11 PM
To: Michael Fuhr
Cc: Jan Meyland Andersen; pgsql-sql@postgresql.org
Subject: Re: [SQL] Related tables to a view
> You could query pg_depend to find out which tables and columns the
> view's rewrite rule depends on but that's not as specific as what
> you're requesting. I'm not aware of a way to associate a particular
> table column with a particular view column short of parsing the view
> definition or rule action; doing so would have to allow for the
> possibility of a view column deriving its value from an arbitrarily
> complex expression involving multiple tables, subqueries, etc.
I have been thinking the problem through again, and I think I am able to
solve the problem if I just know which tables the view is using.
But how do I get this information from the pg_depend table?
Regards
Jan
---------------------------(end of broadcast)---------------------------
TIP 6: explain analyze is your friend
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: Related tables to a view
2006-12-25 21:52 Related tables to a view Jan Meyland Andersen <jma@agile.dk>
2006-12-26 04:10 ` Re: Related tables to a view Michael Fuhr <mike@fuhr.org>
2006-12-26 20:10 ` Re: Related tables to a view Jan Meyland Andersen <jma@agile.dk>
2006-12-26 20:27 ` Re: Related tables to a view Jim Buttafuoco <jim@contactbda.com>
@ 2006-12-27 15:58 ` Jan Meyland Andersen <jma@agile.dk>
0 siblings, 0 replies; 6+ messages in thread
From: Jan Meyland Andersen @ 2006-12-27 15:58 UTC (permalink / raw)
To: Jim Buttafuoco <jim@contactbda.com>; +Cc: pgsql-sql
> Try this query
>
>
> select a.relname as base,a.relkind
> from
> pg_class a
> join pg_depend d on (a.oid = d.refobjid)
> join pg_class c on (d.classid = c.oid)
> join pg_rewrite r on (objid = r.oid)
> join pg_class v on (ev_class = v.oid)
> where a.relkind in('r', 'v')
> and a.relname <> v.relname
> and v.relname='YOUR VIEW NAME HERE'
> order by 1
>
Thanks a lot. That is exactly what I need.
Regards
Jan
^ permalink raw reply [nested|flat] 6+ messages in thread
end of thread, other threads:[~2006-12-27 15:58 UTC | newest]
Thread overview: 6+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2006-12-25 21:52 Related tables to a view Jan Meyland Andersen <jma@agile.dk>
2006-12-26 04:10 ` Michael Fuhr <mike@fuhr.org>
2006-12-26 10:54 ` Jan Andersen <jma@agile.dk>
2006-12-26 20:10 ` Jan Meyland Andersen <jma@agile.dk>
2006-12-26 20:27 ` Jim Buttafuoco <jim@contactbda.com>
2006-12-27 15:58 ` Jan Meyland Andersen <jma@agile.dk>
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox