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August 2017

Upgrading an Amazon EC2 Delphix Target, Part IV

It’s finally time to upgrade our Linux Target!  OK, so we’re not going to upgrade the way a DBA would normally upgrade a database server when we’re working with virtualization.

So far, we’ve completed:

  • 1.  Updating our instances so that we’ll have a GUI interface if we’ll need one.
  • 2.  Installed Oracle on the Linux Source and upgraded our Dsource database to 12c


Now we’re done with our Linux Source and onto our Linux Target.

Presentation – Working with Oracle Database in VB.Net with ODP.Net and Visual API Toolkit; Enhancing Visual Manufacturing 9.0.0

August 7, 2017 A few weeks ago I gave a presentation to a regional group of ERP users, some with an Oracle Database backend and some with a Microsoft SQL Server backend.  The original intention for the presentation was to demonstrate an application package that I created the previous year which maintains and manages production […]

Postgres vs. Oracle access paths IV – Order By and Index

I realize that I’m talking about indexes in Oracle and Postgres, and didn’t mention yet the best website you can find about indexes, with concepts and examples for all RDBMS: You will probably learn a lot about SQL design. Now let’s continue on execution plans with indexes.

Little Things Doth Crabby Make – Part XXII. It’s All About Permissions, Dummy. I Mean yum(8).

Good grief. This is short and sweet, I know, but this installment in the Little Things Doth Crabby Make series is just that–short and sweet. Or, well, maybe short and sour?

Not root? Ok, yum(8), spew out a bunch of silliness at me. Thanks.

Sometimes, little things doth, well, crabby make!

Exadata Capacity on Demand and Elastic Rack

Since X4 we can do Capacity on Demand on Exadata: disable some CPU cores to lower cost of Oracle Database licenses. Depending on the models, and the configuration, there are different minimums and here is a recap table about those.

Here is the summary of Capacity on Demand minimum, maximum and increment. Those numbers come from the configuration file of OEDA, the Oracle Exadata Deployment Assistant ( and you can see that it already has an option for Exadata X7-2

Friday Philosophy – Sometime The Solution Has To Not Only Match The Problem But Also…

…The People!

When you design a system for end users, a good designer/developer considers the “UX” – User eXperience. The system has to be acceptable to the end user. This is often expressed as “easy to use” or “fun” or “Quick”. But in reality, the system can fail in all sort of ways but still be a success if the end user gets something out of using it. I’ve said it before and I’ll say it again and again until I give up on this career. In my opinion:

User Acceptance is the number one aim of any I.T. system.

Successful Evangelism

I’ve been asked what it takes to be a successful evangelist and realizing that what makes one successful at it, is often like holding sand in your hands- no matter how tightly you hold your fists, it’s difficult to contain the grains.

The term evangelist is one that either receives very positive or very negative responses.  I’m not a fan of the term, but no matter if you use this term or call them advocates, representative, influencer-  it doesn’t matter, they are essential to the business, product or technology that they become the voice for.

Those that I view as successful evangelists in the communities that I am part of?

Postgres vs. Oracle access paths III – Partial Index

In the previous post I said that an Index Only Access needs to find all rows in the index. Here is a case where, with similar data, Postgres can find all rows but Oracle needs additional considerations.

In the previous post I’ve executed:
select sum(n) from demo1
The execution plan was:

Aggregate (cost=295.29..295.30 rows=1 width=8) (actual time=2.192..2.193 rows=1 loops=1)
Output: sum(n)
Buffers: shared hit=30
-> Index Only Scan using demo1_n on public.demo1 (cost=0.29..270.29 rows=10000 width=4) (actual time=0.150..1.277 rows=10000 loops=1)
Output: n
Heap Fetches: 0
Buffers: shared hit=30

Random null value in plsql generated data

I have added another small feature to the testdata library. The ability to create random data is good, but
sometimes you also need to have "gaps" in that data. So I made it possible to randomly create null instead of a
value for any generated field. Simply surround the generator function in parentheses and add how big a percentage the chance
are of a null value after the parentheses.

Rebuilding Indexes

One of the special events that can make it necessary to rebuild an index is the case of the “massive DML”, typically a bulk delete that purges old data from a table. You may even find cases where it’s a good idea to mark a couple of your indexes as unusable before doing a massive delete and then rebuild them after the delete.

Despite the fact that a massive delete is an obvious special case it’s still not necessary in many cases to worry about a rebuild afterwards because the space made free by the delete will be smoothly reused over time with very little variation in performance. There is, however, one particular feature that increases the probability of a rebuild becoming necessary – global (or globally partitioned) indexes on partitioned tables. The problem (and the absence of problem in non-partitioned tables) is in the nature of the rowid.