Hi all,

I'm just experimenting with schema usage. I'm going to use it as a fake 'multi-database' system. Is Postgresql support coding schema name using string variable so I can pass it with parameter? I'm give u an example:

I have schema: D200401,D200402.D200403,D200404, etc.

I've set my user just like the schema name, so who login with D200401 will be using D200401 schema. When someone using D200401 schema, they sometime want to access another schema, so in my thought I can use variable like this:

sPointer='D200403'

select * from sPointer.myTable -- Question: How to write it to work properly?

Thanks


William


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Christoph,

First, is it safe for multi user? I mean maybe first user need working with D200402, second one need with D200403, if I do this in first user connection:

SET search_path to D200402 ;

does it affect to the second user search path?

Second, I want it dinamic. So, if I want to using D200402, I just need to pass 'D200402' string in the argument of the function. Got my point?

Thanks anyway,

William



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On Wed, 12 May 2004, William Anthony Lim wrote:

No, search paths are session vars.

You should be able to do it with dot notation:

postgres=# create schema a;
CREATE SCHEMA
postgres=# create schema b;
CREATE SCHEMA
postgres=# create table a.test (info text);
CREATE TABLE
postgres=# create table b.test (info text);
CREATE TABLE
postgres=# insert into a.test values ('abc');
INSERT 1400496 1
postgres=# insert into b.test values ('123');
INSERT 1400497 1

-- Now we try to look up the table without setting a search path and no
-- dot notation:

postgres=# select * from test;
ERROR: relation "test" does not exist
ERROR: relation "test" does not exist

-- Now we set the search path, notice the order:

postgres=# set search_path=public,a,b;
SET
postgres=# select * from test;
info
------
abc
(1 row)

-- Reverse the order of a and b

postgres=# set search_path=public,b,a;
SET
postgres=# select * from test;
info
------
123
(1 row)

-- now without a

postgres=# set search_path=public,b;
SET
postgres=# select * from test;
info
------
123
(1 row)

postgres=# set search_path=public,a;
SET
postgres=# select * from test;
info
------
abc
(1 row)

-- Now we use dot notation. first a, then b. Notice that
-- b, which isn't in our search path, works fine.

postgres=# select * from a.test;
info
------
abc
(1 row)

postgres=# select * from b.test;
info
------
123
(1 row)



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There is something still annoying me Scott..

eg: I want to have function that take a string argument that indicates which schema i want to use.

create function testf(varchar)
returns ...
...
...
...
...

My question is how to use the argument in the function, maybe looks like:

select * from $1.test

or

set search_path to $1
select * from test

or maybe I defined a string variable to hold it,

workschema='D200402'
select * from workschema.test

Do they work?

Thanks,

William



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SET search_path to D200402 ;
....
should do the job.

Regards, Christoph


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