TOI

How to fix a problem with the spfile in #Oracle

An invalid entry in the spfile may prevent the instance from starting up:

SQL> alter system set sga_target=500m scope=spfile;

System altered.

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORA-00821: Specified value of sga_target 512M is too small, needs to be at least 1392M

The instance doesn’t come up! This is easy to fix without having to restore the spfile from backup:

SQL> create pfile='/home/oracle/init.ora' from spfile;

File created.

SQL> host vi /home/oracle/init.ora

Now correct the value in the text file. I just removed the sga_target parameter from it here. Then

Index Competition in #Oracle 12c

Suppose you want to find out which type of index is best for performance with your workload. Why not set up a competition and let the optimizer decide? The playground:

Data Redaction and Data Pump in #Oracle 12c

What happens upon Data Pump Export if tables are being exported that have a Data Redaction Policy? I got that question several times in class, which is why I put the answer here , so I can refer to it subsequently.  Might also be of interest to the Oracle Community:-)

Create a SQL Profile to let the Optimizer ignore hints in #Oracle

Something I presented recently during an Oracle Database 12c Performance Management and Tuning class. Hints are a double-edged sword; they may do more harm than good. What if  hinted SQL comes from an application that you as the DBA in charge can’t modify? You can tell the Optimizer to ignore that nasty hint.

One method is to use alter session set “_optimizer_ignore_hints”=true; This will make the optimizer ignore all hints during that session  – also the useful ones, so maybe that is not desirable. The method I show here works on the statement level. The playground:

Another reason why you should use the Data Guard Broker for your #Oracle Standby

The Data Guard Broker is recommended for various reasons, this one is less obvious: It prevents a Split-Brain problem that may otherwise occur in certain situations. Let me show you:

FREE Webinar: Efficient techniques to create and maintain your #Oracle Standby Database

Join us with this FREE event on May 19, 13:00 CET and register now, because seats are limited.

DataGuard_Lunchtime_Webinar

I will be talking about

  • how to create and maintain a 12c Standby Database in the most efficient way
  • how to do switchover and failover
  • how to keep up client connectivity after role changes

These topics will be live demonstrated – positively no slide show reading.

Speakers: Put your Twitter Handle on the Windows taskbar!

If you speak often at conferences, sharing your screen to demo things, this could be helpful:

Twitter Handle on the Windows taskbar

Throughout your presentation, the audience will be able to see your Twitter Handle, reminding them to include it with tweets about the event. I used to include it in the slides, but this is better, because it works also with live demonstrations where no slides are being showed. Which is incidentally my favorite way to do presentations:-)

Turkish Oracle User Group Conference in Istanbul 2016 #TROUGDays

Straight after the Oracle University Expert Summit in Berlin – which was a big success, by the way – the circus moved on to another amazing place: Istanbul!

Istanbul viewThe Turkish Oracle User Group (TROUG) did its annual conference in the rooms of the Istanbul Technical University with local and international speakers and a quite attracting agenda.

Do you recognize anyone here?:-)

DEFAULT_CACHE_SIZE mentioned in alert.log of an #Oracle database

Today, I got this message in my alert.log file:

Full DB Caching disabled: DEFAULT_CACHE_SIZE should be at least 709 MBs bigger than current size.

When I look at the datafile sizes and compare them with the buffer cache size, it shows:

 

#Oracle University Expert Summit Berlin 2016

Join us in Berlin, 18th – 20th April. The event will take place at the Adlon Hotel with Jonathan Lewis, Pete Finnigan, Christian Antognini, Javier de la Torre Medina and myself as speakers. We have over 70 enrollments already, so take action to secure your seat in time!

Expert Summit Berlin 2016