Blogs

If you ever used the Solaris ps -ef command to view programs that are running you may not always see the arguments the original program was started with. This command usually shows about 80 characters.

Try the following commands, they usually give you more information about the command that started the process running. Depending on the patch level of your OS you may see 200 characters or more.

/usr/ucb/ps
/usr/ucb/ps -auxwww

-Dave

I ran across Orion in a Kevin Closson blog post. From the OTN site:

"ORION (Oracle I/O Calibration Tool) is a standalone tool for calibrating the I/O performance for storage systems that are intended to be used for Oracle databases. The calibration results are useful for understanding the performance capabilities of a storage system, either to uncover issues that would impact the performance of an Oracle database or to size a new database installation. Since ORION is a standalone tool, the user is not required to create and run an Oracle database. "

As I get deeper into tuning with Statistics and the CBO I have been paying a lot more attention to hints.

In the past I always tried to avoid hints. After working with the CBO and staistics in recent versions I believe they are necessary at times to give guidance to the CBO.

The Oracle Database SQL Language Reference has a comprehensive list of hints included in the documentation of SQL Comments. The list for 11g is available here: link.

I have been making use of the GATHER_PLAN_STATISTICS hint more and more lately. In the interest of getting the most accurate data I usually log in as the user that normally executes the query. These are usually non-privileged accounts that just have access to their own objects.

In order to use DBMS_XPLAN.DISPLAY_CURSOR in a session that does not have DBA or SELECT CATALOG ROLE, grant the following permissions to them:

SQL> GRANT SELECT ON V_$SESSION TO &&MYUSER;
SQL> GRANT SELECT ON V_$SQL TO &&MYUSER;

For the past few weeks I have been using the TriVaDis eXtended Tracefile Analysis Tool as a replacement for TKPROF.

TKPROF is available with all Oracle installations but is has some drawbacks. Early versions of TKPROF do not provide any information about bind variables. It also tends to lose detail because it aggregates data. When performing analysis it is unwise to make inferences about detailed execution based on aggregates. TVD$XTAT provides aggregates but also provides detail on each SQL Statement so you can zero in on the statement of interest.

I was recently looking for old (not ancient, just old) install media to support a database migration. The usual collection of download links on OTN usually just has the last 2 releases. If you need older versions (in this case 9i) then hit up the EDelivery site and you should be able to find them.

http://edelivery.oracle.com/

If you need a much older version (like 8i or gasp! 7) I have heard you may be able to obtain it through an SR if you have a current support contract but luckily I have not had to test that route.

On Oracle-L there was a recent discussion about detecting block corruption.

One suggestion was to do an Export to /dev/null. While this may get you 95% of the way there it is mainly relying on side effects of data access to detect any issues. If blocks are cached then it might not root out physical corruption.

Iggy Fernandez covers the topic of who is better suited to tune SQL - Developers or DBAs. Also listed are 5 Dangerous Beliefs which may influence the answer to that question.

https://iggyfernandez.wordpress.com/2009/07/12/who-should-tune-sql-the-dba-or-the-developer/

-Dave

Here is some code to update the previous widget to show data in a green/yellow/red bar graph like an audio meter:

The code is here:

CREATE OR REPLACE FUNCTION GetGraph (p_value IN NUMBER, p_total IN NUMBER DEFAULT 100)
RETURN VARCHAR2
IS

-- David Mann
-- 05/26/2009
-- Create HTML bar graph widget for use in Application Express reports.
-- Has thresholds for yellow and red.
-- Parameters: p_value - Top of ratio fraction or percentage as whole number (0-100)

I'm trying not to scare my users off with endless rows and columns of numbers. I have an app that analyzes memory usage and swap space usage of some of our servers. Instead of throwing all kinds of computer sciency '65535' and '32767' numbers at my user I decided to create a small function to return a bar graph widget.

Here is an example of the graph in use:

Here is a function that will return the HTML for the widget:

CREATE OR REPLACE FUNCTION GetGraph (p_value IN NUMBER, p_total IN NUMBER)