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March 2016

DB2 fully supported on Delphix

I’ve received a number of inquiries lately about the support of DB2 on Delphix and yes, Delphix 5.0 now supports full automation of virtual data for DB2. With the addition of DB2, Delphix now supports full automation of virtual data on all three of the major enterprise databases

  • Oracle
  • SQL Server
  • DB2

as well as Sybase, MySQL and Postgres.

For more information on DB2 in Delphix 5.0 see

and here is a video demoing DB2 on Delphix 5.o

Index Speculation

There’s a current question on the OTN database forum as follows (with a little cosmetic adjustment):

I have a request for 3 indices as shown below. Does the 1st index suffice for 2 and 3?  Do I need all 3?

  • create index idx_atm_em_eff_ver_current_del on atm_xxx_salary (employee_key, effective_dt, salary_version_number, is_current, is_deleted);
  • create index idx_atm_em_ver_current on atm_xxx_salary (employee_key, salary_version_number, is_current);
  • create index .idx_atm_sal_current_del on atm_xxx_salary (employee_key, is_deleted, is_current);

In the absence of any information about the data and the application the correct answer is: “How could we possibly tell?”

Collaborate 16: My sessions

I’ll be at Collaborate 16 next month and looking forward to seeing lots of good friends, learning some new things, and sharing a little experience too. For the last of those, I’ll present 3 sessions, er, more like 2.2 sessions:

Adding GPIO Pins to the Raspberry Pi Zero

Although the Raspberry Pi 3 is now available, many people are still interested in it’s cheaper, smaller version, the Raspberry Pi Zero.

Hinting

A posting on the OTN database forum a few days ago demonstrated an important problem with hinting – especially (though it didn’t come up in the thread)  in the face of upgrades. A simple query needed a couple of hints to produce the correct plan, but a slight change to the query seemed to result in Oracle ignoring the hints. The optimizer doesn’t ignore hints, of course, but there are many reasons why it might have appeared to so I created a little demonstration of the problem – starting with the following data set:

Views as “stored text”

You’ll often see comments that views are not copies of the data, they are merely the stored text of a query that defines.

This is by and large true, but don’t forget, this is not  the same as saying we simply take whatever text you give us, and store it.

Let’s take a look at a simple example proving that this is not the case.

RMOUG’s Movie Night and WIT Panel

Last night I attended our RMOUG WIT’s movie night.  We partnered with Regis and the choice in movie has received a lot of great reviews, titled, Code-  Debugging the Gender Gap.

New Series of EM Blog Posts

One thing I like seeing is how people use Enterprise Manager. It’s one of the most enjoyable parts of speaking at conferences (apart from the social networking, of course), because quite often the users of Enterprise Manager find ways of using the product that we in Product Management might never have thought of. Sometimes that can lead to useful product enhancements, and other times it leads to much head shaking in disbelief (but since I don’t like exposing that side much you’ll have to grab me at a conference to hear some of those more “interesting” examples!)

Oracle Midlands : Event #14 – Summary

Last night was Oracle Midlands Even #14 with Lothar Flatz.

The session started with “Raiders of the Data Dictionary I: Indexing for the Workload” where Lothar discussed a project he worked on based around completely revamping the indexing of a system. I guess the best way I can describe it is to say it’s a more scientific approach to indexing, using the contents of the dictionary to provide information about columns and column groups used in queries to determine the indexes to create. In some ways the approach was quite extreme (throw everything away and start again), but I also admire the bravery of that approach!

Database dictionary corruption ? Maybe not.

At first glance, this looks like a major drama. Some sort of database dictionary corruption, or internal error. But we’ll see, it’s actually fine.

Let’s do a simple describe on an existing table


SQL> desc MY_TABLE
 Name                          Null?    Type
 ----------------------------- -------- --------------------
 EMPNO                                  NUMBER(38)
 ENAME                                  VARCHAR2(30)
 HIREDATE                               DATE
 DEPTNO                                 NUMBER(38)
 SAL                                    NUMBER(38)

Now of course, that could a synonym, or a view… so let’s also make sure that we are actually dealing with a real table.