Thread: Query about using arrays (for accessing pg_group)

Howdy,

Am trying to implement a user/group based security model for
accessing a database which is tightly integrated with the postgresql
security model.

The problem I am having is that I am not sure how to check which
groups a user is in.

For example, if I have a user (with id of 21) in a group, I'm not
sure how to start off with the user id and pull out the group name
using normal sql.

If I try the half intuitive approach

z=> select groname from pg_group where grolist = 21;
ERROR:  Unable to identify an operator '=' for types '_int4' and 'int4'       You will have to retype this query using
anexplicit cast
 

The cause of my problem is the use of an array to store the user id's
associated with a group. Not sure how to get around this.

Any ideas?

Please cc replies to me as I think I've fallen off this list.

tia,
  -Greg

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www.geelong.com                                       Greg Wickham  P.O. Box 1426
greg@geelong.com
Geelong VIC 3220                             Ph: (+61 407) 854 566
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Greg Wickham <greg@geelong.com> writes:
> If I try the half intuitive approach
> z=> select groname from pg_group where grolist = 21;
> ERROR:  Unable to identify an operator '=' for types '_int4' and 'int4'
>         You will have to retype this query using an explicit cast
> The cause of my problem is the use of an array to store the user id's
> associated with a group. Not sure how to get around this.

You need a function that will return true if any of the elements of
an int4 array is equal to a particular int4 value.  See contrib/array/
for one way to do it.
        regards, tom lane