Re: How can I find the schema that a table belongs to?

Hi,

I am trying to tidy up my perl script that runs as a cgi and allows
remote users (aka me) to interact with my Pg database.

I primarily want to use this tool as a way for my iPad to
browse my data base. It seems to be working quite well but
one certainly does not want to 'select * from ginormous_table'.

I am trying to build a 'describe' function. ie if the user
types "describe tablename" in the sql box I want to display
some interesting attributes for that table, mainly names and
data types for each of the columns.

I have done this in other programs but I forced the user
to specify a schema qualified name ( and mimiced what psql -E
did).

So I guess the question is:
Given a bare table name, how can I recover the schema
qualified name with whatever the current search path happens
to be?

This task has to be done using simple sql from the perl dbi.

Thanks,

Jerry

one of the way to find out schema name is like below

select * from pg_tables where tablename like '%xyz%';
schemaname | tablename | tableowner | tablespace | hasindexes | hasrules |
hastriggers
------------+-----------+------------+------------+------------+----------+-------------
(0 rows)

~Deepak

On Wed, Jan 19, 2011 at 8:26 AM, Jerry LeVan <jerry(dot)levan(at)mac(dot)com> wrote:

> Hi,
>
> I am trying to tidy up my perl script that runs as a cgi and allows
> remote users (aka me) to interact with my Pg database.
>
> I primarily want to use this tool as a way for my iPad to
> browse my data base. It seems to be working quite well but
> one certainly does not want to 'select * from ginormous_table'.
>
> I am trying to build a 'describe' function. ie if the user
> types "describe tablename" in the sql box I want to display
> some interesting attributes for that table, mainly names and
> data types for each of the columns.
>
> I have done this in other programs but I forced the user
> to specify a schema qualified name ( and mimiced what psql -E
> did).
>
> So I guess the question is:
> Given a bare table name, how can I recover the schema
> qualified name with whatever the current search path happens
> to be?
>
> This task has to be done using simple sql from the perl dbi.
>
> Thanks,
>
> Jerry
>
>
>
> --
> Sent via pgsql-general mailing list (pgsql-general(at)postgresql(dot)org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-general
>

On Jan 19, 2011, at 3:12 PM, DM wrote:

> one of the way to find out schema name is like below
>
> select * from pg_tables where tablename like '%xyz%';
> schemaname | tablename | tableowner | tablespace | hasindexes | hasrules | hastriggers
> ------------+-----------+------------+------------+------------+----------+-------------
> (0 rows)
>
> ~Deepak
>

That does not work if the user entered a 'view' in the sql box.

Also a table/view could be in several schemas...

Jerry

If your looking for Views then you could use pg_views ==> select * from
pg_views limit 1;

Here is one more, there was a recent post same as your request, Please see
the below email, hope this helps you

Tom Lane =================>
Thomas Kellerer <spam_eater(at)gmx(dot)net> writes:
> Jerry LeVan, 19.01.2011 17:35:
>> So I guess the question is:
>> Given a bare table name, how can I recover the schema
>> qualified name with whatever the current search path happens
>> to be?

> SELECT table_schema
> FROM information_schema.tables
> WHERE table_name = 'your_table'
> ;

That's not going to work, at least not in the interesting case where you
have more than one candidate table --- that SELECT will list all of 'em.

In most cases the answer to this type of problem is "use regclass",
but regclass doesn't quite solve Jerry's problem because it won't
schema-qualify the name if the table is visible in the search path.
The best solution I can think of is

select nspname from pg_namespace n join pg_class c on n.oid = c.relnamespace
where c.oid = 'my_table_name'::regclass;

which works but seems a bit brute-force.

regards, tom lane
- Hide quoted text -

==========================================>

On Wed, Jan 19, 2011 at 12:58 PM, Jerry LeVan <jerry(dot)levan(at)mac(dot)com> wrote:

>
> On Jan 19, 2011, at 3:12 PM, DM wrote:
>
> > one of the way to find out schema name is like below
> >
> > select * from pg_tables where tablename like '%xyz%';
> > schemaname | tablename | tableowner | tablespace | hasindexes | hasrules
> | hastriggers
> >
> ------------+-----------+------------+------------+------------+----------+-------------
> > (0 rows)
> >
> > ~Deepak
> >
>
> That does not work if the user entered a 'view' in the sql box.
>
> Also a table/view could be in several schemas...
>
> Jerry
>

or you could use the below query

********* QUERY **********
SELECT n.nspname as "Schema",
c.relname as "Name",
CASE c.relkind WHEN 'r' THEN 'table' WHEN 'v' THEN 'view' WHEN 'i' THEN
'index' WHEN 'S' THEN 'sequence' WHEN 's' THEN 'special' END as "Type",
pg_catalog.pg_get_userbyid(c.relowner) as "Owner"
FROM pg_catalog.pg_class c
LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE c.relkind IN ('r','v','S','')
AND n.nspname <> 'pg_catalog'
AND n.nspname <> 'information_schema'
AND n.nspname !~ '^pg_toast'
AND pg_catalog.pg_table_is_visible(c.oid)
AND c.relname like '%my_table_name%'
ORDER BY 1,2;
**************************

On Wed, Jan 19, 2011 at 1:54 PM, DM <dm(dot)aeqa(at)gmail(dot)com> wrote:

> If your looking for Views then you could use pg_views ==> select * from
> pg_views limit 1;
>
> Here is one more, there was a recent post same as your request, Please see
> the below email, hope this helps you
>
> Tom Lane =================>
> Thomas Kellerer <spam_eater(at)gmx(dot)net> writes:
> > Jerry LeVan, 19.01.2011 17:35:
>
> >> So I guess the question is:
> >> Given a bare table name, how can I recover the schema
> >> qualified name with whatever the current search path happens
> >> to be?
>
> > SELECT table_schema
> > FROM information_schema.tables
> > WHERE table_name = 'your_table'
> > ;
>
> That's not going to work, at least not in the interesting case where you
> have more than one candidate table --- that SELECT will list all of 'em.
>
> In most cases the answer to this type of problem is "use regclass",
> but regclass doesn't quite solve Jerry's problem because it won't
> schema-qualify the name if the table is visible in the search path.
> The best solution I can think of is
>
> select nspname from pg_namespace n join pg_class c on n.oid =
> c.relnamespace
> where c.oid = 'my_table_name'::regclass;
>
> which works but seems a bit brute-force.
>
> regards, tom lane
> - Hide quoted text -
>
> ==========================================>
>
>
> On Wed, Jan 19, 2011 at 12:58 PM, Jerry LeVan <jerry(dot)levan(at)mac(dot)com> wrote:
>
>>
>> On Jan 19, 2011, at 3:12 PM, DM wrote:
>>
>> > one of the way to find out schema name is like below
>> >
>> > select * from pg_tables where tablename like '%xyz%';
>> > schemaname | tablename | tableowner | tablespace | hasindexes |
>> hasrules | hastriggers
>> >
>> ------------+-----------+------------+------------+------------+----------+-------------
>> > (0 rows)
>> >
>> > ~Deepak
>> >
>>
>> That does not work if the user entered a 'view' in the sql box.
>>
>> Also a table/view could be in several schemas...
>>
>> Jerry
>>
>
>