Sonntag, 22. November 2009

PRKO-2007 is not always correct

This week I had to stop and start an instance in a CRS-cluster. Nothing special so far, I just hit a PRKO-2007 error. For those which does not know it by heart, here the short description:
PRKO-2007: "Invalid instance name: "
Cause: An invalid instance name was entered.
Action: Use the correct instance name for the database. Run 'srvctl config database
-d ' command to find out all instances of a database in the
Cluster Database Configuration.


and here the copy of my commands (solution included):
oracle@aves742p:~/ [EDWP031] srvctl stop instance -d EDWP03 -i EDWP031
PRKO-2007 : Invalid instance name: EDWP031
oracle@aves742p:~/ [EDWP031] srvctl stop instance -d EDWP03_SITE1 -i EDWP031


I'm sure, you see the difference, and it's not the instance!
Just once again: don't trust the error message 100%, sometimes it's still worth to use the brain ;-)

Mittwoch, 11. November 2009

hardware lasts longer than software

2.0
A week ago, Oracle has replaced its good old support platform MetaLink with MyOracleSupport (MOS).
The thing I like most about MOS is the non Flash-based HTML-Version.
Many discussions about the need, target and failures during the last week of transition are ongoing in blogs, mailing lists, forums; I also had to suffer and had to communicate it. But that's not what's this blog is about.

I got into touch with MetaLink in 2000, as Oracle tried to move the customers from calling the Support to a self-service platform. They promoted MetaLink on many events, with everything you can imagine. The transition was not forced, but within a short period of time most customers liked the possibility to get many answers faster than on the phone. A real win-win situation.
Also I learned how to use MetaLink effective and therefore like it.

Metalink iTar

On one of these events, I got the promo-mug. I like it, because I like MetaLink.
Nowadays, everytime I feel without any Support from Oracle, I cling to the mug, hopefully filled with good, strong, hot coffee. This makes me feel a little bit better.
And sometimes, hardware really lasts longer than software, especially if you have the hardware in your hands and take care of.

Dienstag, 10. November 2009

rollback in PL/SQL

I recently came across a slightly, but possible dangerous mismatch between transactions and the PL/SQL code based on it.
Here a cut down example (not very realistic, but easy to follow):

create table mytab (myval number);

create or replace procedure tuwas (
varA in number,
varB in number,
varC OUT number)
is
begin
varC := varA;
insert into mytab values (varA);
if varB = 0 then
commit;
else
rollback;
end if;
end;
/

The Idea behind the code is, to get varA and varB as input parameters, do some calculations (missing here), insert the result into a table and return the calculated value for next steps.
There might be reasons to rollback the DML within the procedure, which is not seen as an error.

And here the result of the procedure:

set serverout on

declare
vA number;
vB number;
vC number;
begin
vA := 1;
vB := 0; -- commit;
tuwas(vA, vB, vC);
dbms_output.put_line('vC: ' ||vC);
vA := 2;
vB := 1; -- rollback;
tuwas(vA, vB, vC);
dbms_output.put_line('vC: ' ||vC);
END;
/

vC: 1
vC: 2

select * from mytab;

MYVAL
----------
1


What's dangerous here? Even with

vA := 2;
vB := 1;
the return value

vC: 2
is given. But t's not visible in the table, as the procedure did a rollback.
I learned from this example never to populate return-values until you are sure it's really stored (if this is a requirement, of course).

Montag, 9. November 2009

Oracle Security Options


Last week I attended a 1 day Seminar about Oracle Security by Dominique Jeunot.
Dominique did a great job to squeeze everything she knows into one day, and it was allways obvious there is a lot more she could tell us in the script and even more in her brain. Nevertheless she created a very good overview with the right level on all topics. It was obvious she could only make a kind of teaser, but it was a very tasty one!
Maybe the most important picture she draw was the first overview about all available features, options and products. I did the effort to draw it for my own joy and will share it here, as it might be helpful for others as well. All options are colored red, so you can see where you have to take extra money.

In general you can say: for nearly every issue there are possibilities to do it without extra money (but extra effort) or you can buy a solution.

If someone wants the visio behind this jpeg, just contact me :)