Tuesday, August 21, 2012

Monday, August 20, 2012

Welcome to Switzerland! Choose your database territory wisely...

One of the many international aspects of living in the Lake Constance region is that you encounter Swiss, Austrian, and German people, and even those from Lichtenstein on a daily basis. Language (mostly the dialect) is the most obvious differentiator in direct contact as well as a license plate on car. Sometimes, there are also the small and funny struggles with technology which show country-specific preferences.

Depending on the weather, it often happens that you walk in downtown Friedrichshafen and suddenly receive a text message "Welcome to Switzerland!" and your mobile phone started roaming using a Swiss mobile phone company instead of your German mobile provider. Similary, depending on the weather again, you can easily pick up a German provider along the Swiss shore or in Romanshorn waiting for a ferry to Germany. Always make sure that your phone has the right provider, else it will be expensive even receiving a call.

Then, there also funny annoyances like Google Maps. It is showing the Swiss-German border in a very liberal way. The German Reichenau island is, according to Google, Swiss territory. Fortunately, the borderline is clear to everyone and the countries are cooperating and helping each other across the lake.

When working with a database system like DB2, you also have to select the territory, codepage and collation for a database. You could have German, Swiss, Austrian (though no Lichtensteinian) databases side by side in a single DB2 instance. One thing you cannot do is to change the territory as we can do on the mobile phone when picking our home provider. So it would continue to say "Welcome to Switzerland!"

Larger Map

Monday, August 13, 2012

Two whales in the air: Zeppelins over Friedrichshafen

Yesterday I got the sudden chance to climb up a church tower in Friedrichshafen. It was also the rare opportunity to see two Zeppelins side by side (taken with my mobile phone). One had just departed with new passengers, the other was approaching the Zeppelin landing site.
What can also be seen close to the center is the runway of Friedrichshafen Airport, on the left of it the Zeppelin hangar and the Friedrichshafen Messe (expo & fair). The open space in the foreground on the right will be home to the new headquarters of ZF.

Tuesday, August 7, 2012

Partial early blog posting

Two of the many performance enhancements in DB2 10.1 are called PED (partial early distinct) and PEA (partial early aggregation). Work is done as early as possible, though only partially, to reduce data volume already in an early stage and speed up the total query. Having said that, I am done. :)

P.S.: This may be only partial information on PED and PEA, but it helps you speed up query performance and is light in reading...

Wednesday, August 1, 2012

Vacation: Time to REBALANCE (and to look at DB2 10)

It is vacation time, time to recharge and to rebalance life (BTW: Some years back some companies talked about work-life balance, now it is "work/life integration" - towards always on). When I thought about "rebalance", some new DB2 features came to mind. You see, I am still in work mode...

When changing storage in DB2, e.g., adding containers to a tablespace or removing them from it, the tablespace is rebalanced to keep it evenly striped. DB2 10 introduced the concept of storage groups. It allows to group tablespaces with similar properties or "tasks" together. Using ALTER TABLESPACE it is possible to change the associated storage group. To move the data from the former to the new storage (group), data is rebalanced in the background, i.e., asynchronously. To have greater control over those background tasks, DB2 10 adds SUSPEND and RESUME to the ALTER TABLEPACE ... REBALANCE statements. So you can decide when to take a break...

As you might know, there is another rebalance operation available in DB2, storage-related again. It is used in pureScale environments after changes to the shared file system (cluster file system) and rebalances storage utilization. The rebalance option is part of the db2cluster command which is used to interact with the reliable, scalable cluster infrastructure (RSCT) and the cluster file system GPFS.

As both rebalance operations are recommended for "periods of low system activity", this could mean vacation time - bringing me back to what I am preparing for...