Re: What stupid mistake am I making with this onlogin trigger?

From: Nigel Thomas <nigel_cl_thomas_at_yahoo.com>
Date: Tue, 26 Feb 2008 04:13:46 -0800 (PST)
Message-ID: <269339.67503.qm@web58812.mail.re1.yahoo.com>

Small extra point:

IMHO it's not best practice to use v$ views when you could use SYS_CONTEXT and DBMS_APPLICATION_INFO instead - so you don't have to have too many users with unrestricted read access to some or all of the v$ views. It's always a good idea to minimise the scope of any grants.

(select unique(sid) from v$mystat)

can be replaced with:
  SYS_CONTEXT('userenv','sessionid')

which has the added benefit of avoiding a hash(unique) on v$mystat (370 rows in my case).

To demonstrate:

declare

 l_module varchar2(48);
 l_action varchar2(32);
 l_username varchar2(30);
 l_sid integer;

begin
 dbms_application_info.read_module_info(l_module, l_action);  l_username := sys_context('userenv','session_user');  l_sid := sys_context('userenv','sessionid');

 dbms_output.put_line('User:'||l_user||', SID:'||l_sid||', Module:'||l_module);

end;
/

Shame that DBMS_APPLICATION_INFO doesn't have usable GET_xxx functions, but forces the use of a procedure with output parameters. How 1960s is that? Also, in some circumstances it might be appropriate to cover DBMS_APPLICATION_INFO with a package that only allows gets, not sets.

NB I haven't compared the cost of these with accessing the views.

Regards Nigel

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Received on Tue Feb 26 2008 - 06:13:46 CST