Comments on: Undocumented LNNVL SQL function now safe to use http://awads.net/wp/2006/05/02/undocumented-lnnvl-sql-function-now-safe-to-use/ News, views, tips and tricks on Oracle and other fun stuff Thu, 07 Aug 2008 23:45:16 +0000 http://wordpress.org/?v=2.5 By: Laurent Schneider http://awads.net/wp/2006/05/02/undocumented-lnnvl-sql-function-now-safe-to-use/#comment-50019 Laurent Schneider Tue, 26 Sep 2006 09:52:14 +0000 http://awads.net/wp/2006/05/02/undocumented-lnnvl-sql-function-now-safe-to-use/#comment-50019 <p>I would not even pretend it is safe to use in 10g !</p> <p>SQL> select * from dual where not lnnvl(1=1); select * from dual where not lnnvl(1=1) * ERROR at line 1: ORA-03113: end-of-file on communication channel</p> I would not even pretend it is safe to use in 10g !

SQL> select * from dual where not lnnvl(1=1);
select * from dual where not lnnvl(1=1)
*
ERROR at line 1:
ORA-03113: end-of-file on communication channel

]]> By: Karl http://awads.net/wp/2006/05/02/undocumented-lnnvl-sql-function-now-safe-to-use/#comment-5505 Karl Wed, 03 May 2006 19:31:29 +0000 http://awads.net/wp/2006/05/02/undocumented-lnnvl-sql-function-now-safe-to-use/#comment-5505 <p>Now i wait for an article about the spivns() undocumented oracle function. It starts a space invaders clone. And guess the unlimited dbms_output buffering introduced in 10.2 was the base for it! ;-) Karl</p> Now i wait for an article about the spivns() undocumented oracle function. It starts a space invaders clone. And guess the unlimited dbms_output buffering introduced in 10.2 was the base for it! ;-) Karl

]]> By: Eddie Awad http://awads.net/wp/2006/05/02/undocumented-lnnvl-sql-function-now-safe-to-use/#comment-5500 Eddie Awad Wed, 03 May 2006 18:56:00 +0000 http://awads.net/wp/2006/05/02/undocumented-lnnvl-sql-function-now-safe-to-use/#comment-5500 <p>Chuck, thanks for digging it up in 10.1.</p> <p>I thought that the "search across the documentation libraries" should have returned results from 10.1 also, but it looks like this is not the case!</p> <p>I have updated the post accordingly. Thanks again.</p> Chuck, thanks for digging it up in 10.1.

I thought that the “search across the documentation libraries” should have returned results from 10.1 also, but it looks like this is not the case!

I have updated the post accordingly. Thanks again.

]]> By: Chuck http://awads.net/wp/2006/05/02/undocumented-lnnvl-sql-function-now-safe-to-use/#comment-5498 Chuck Wed, 03 May 2006 18:40:53 +0000 http://awads.net/wp/2006/05/02/undocumented-lnnvl-sql-function-now-safe-to-use/#comment-5498 <p>I did see it in the 10.1 docs. Oddly enough the Super Oracle search engine at tahiti didn't find it when searching across all docs. Drilling into the 10.1 link and searching did reveal to docs.</p> <p>http://download-west.oracle.com/docs/cd/B14117_01/server.101/b10759/functions068.htm#i1479295</p> I did see it in the 10.1 docs. Oddly enough the Super Oracle search engine at tahiti didn’t find it when searching across all docs. Drilling into the 10.1 link and searching did reveal to docs.

http://download-west.oracle.com/docs/cd/B14117_01/server.101/b10759/functions068.htm#i1479295

]]> By: Eddie Awad http://awads.net/wp/2006/05/02/undocumented-lnnvl-sql-function-now-safe-to-use/#comment-5431 Eddie Awad Wed, 03 May 2006 00:01:10 +0000 http://awads.net/wp/2006/05/02/undocumented-lnnvl-sql-function-now-safe-to-use/#comment-5431 <p>Gary, you have valid concerns. The advice has always been to avoid using undocumented features.</p> <p>The fact that LNNVL has been internally used by the Oracle optimizer (shows up in the query plan in certain situations) in versions prior to 10g, and that LNNVL has been officially documented in 10gR2, make it less of a concern (to me at least) if I want to use it in 9i for example, especially when I know that I will upgrade to 10gR2 in the near future.</p> Gary, you have valid concerns. The advice has always been to avoid using undocumented features.

The fact that LNNVL has been internally used by the Oracle optimizer (shows up in the query plan in certain situations) in versions prior to 10g, and that LNNVL has been officially documented in 10gR2, make it less of a concern (to me at least) if I want to use it in 9i for example, especially when I know that I will upgrade to 10gR2 in the near future.

]]> By: Gary http://awads.net/wp/2006/05/02/undocumented-lnnvl-sql-function-now-safe-to-use/#comment-5429 Gary Tue, 02 May 2006 23:35:55 +0000 http://awads.net/wp/2006/05/02/undocumented-lnnvl-sql-function-now-safe-to-use/#comment-5429 <p>"So, if you’re stuck with Oracle 8i or 9i, you can safely use the undocumented LNNVL function, knowing that it has become documented and supported in 10g."</p> <p>I think 'safely' may be going a little to far. I'd be wary about using any feature prior to the version in which it was documented, as there may have been reasons why it was left undocumented. In this case, my main concern would be whether the CBO is able to correctly determine costs/selectivity/cardinality for that condition. I'd probably have reservations about using it with 'exotic' datatypes too.</p> “So, if you’re stuck with Oracle 8i or 9i, you can safely use the undocumented LNNVL function, knowing that it has become documented and supported in 10g.”

I think ’safely’ may be going a little to far. I’d be wary about using any feature prior to the version in which it was documented, as there may have been reasons why it was left undocumented.
In this case, my main concern would be whether the CBO is able to correctly determine costs/selectivity/cardinality for that condition. I’d probably have reservations about using it with ‘exotic’ datatypes too.

]]>