[GRASS-dev] Re: [GRASS-user] Views in pgSQL
mlennert at club.worldonline.be
Wed Apr 11 11:25:24 EDT 2007
On 11/04/07 13:48, Jarosław Jasiewicz wrote:
> Moritz Lennert napisał(a):
>> On 11/04/07 13:01, Jarosław Jasiewicz wrote:
>>> Is still possible to use pgSQL views to connect vectors?
>>> Connecting views was possible for or five month ago (in spite of
>>> error messages during creating views).
>>> I have some vector joinred to view They still working. But now, when
>>> I tried to connect new vector with view I recived simple error
>>> message that there is no table I plan to join
>> What is the exact error message you are receiving.
>>> If that possibilites was removed (after my post, unfortunatly) please
>>> let me know
>> I am not aware of any related changes...
Sorry, I spoke to fast. I think I now found the culprit:
date: 2006/11/28 08:42:02; author: markus; state: Exp; lines: +1 -1
if table doesn't exist: fatal error
Before it was only a warning, not a fatal error, and so the connection
was established and worked.
This undoes what Radim did two years earlier:
date: 2004/11/25 13:15:47; author: radim; state: Exp; lines: +2 -2
error -> warning if table does not exist
Markus, what was the reason that you changed this ?
Either we have to revert this again, or we have to find a way to check
for views as well as tables, which means either implementing
db_view_exists() (with all the individual implementations, or just
modify the list_tables functions of the individual drivers to include
views. In the PostgreSQL driver, the statement used is ( ):
"select * from pg_tables where tablename !~ 'pg_*' order by tablename"
For views this would have to be something like:
SELECT viewname FROM pg_views WHERE schemaname NOT IN
('pg_catalog','information_schema') AND viewname !~ '^pg_';
So the results of these two calls would have to be combined before
db__driver_list_tables() returns the results.
I don't know if there are any good reasons not to just include views
into the list of tables...
In the meantime, you can just modify v.db.connect at line 231 from
G_fatal_error(_("Table <%s> does not exist in database
G_warning(_("Table <%s> does not exist in database
> Pg Views are very important for me when I connect-reconnect vector files
> to different atribute table. I use (used!) views insted of original
> table to avoid occasional removing original data and to speed up
> transfer limiting data in views only to these needed for
> (sorry, I think everybody knows it)
I completely agree with you. Being able to connect maps to views is
fundamental in my eyes.
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