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January 2016

Drop Column

I published a note on AllthingsOracle a few days ago discussing the options for dropping a column from an existing table. In a little teaser to a future article I pointed out that dropping columns DOESN’T reclaim space; or rather, probably doesn’t, and even if it did you probably won’t like the way it does it.

I will  be writing about “massive deletes” for AllthingsOracle in the near future, but I thought I’d expand on the comment about not reclaiming space straight away. The key point is this – when you drop a column you are probably dropping a small fraction of each row. (Obviously there are some extreme variants on the idea – for example, you might have decided to move a large varchar2() to a separate table with shared primary key).

DML Operations On Partitioned Tables Can Restart On Invalidation

It's probably not that well known that Oracle can actually rollback / re-start the execution of a DML statement should the cursor become invalidated. By rollback / re-start I mean that Oracle actually performs a statement level rollback (so any modification already performed by that statement until that point gets rolled back), performs another optimization phase of the statement on re-start (due to the invalidation) and begins the execution of the statement from scratch.


Oracle 12c – PL/SQL in SELECT

It is often useful to execute PL/SQL functions as part of an SQL SELECT statement (or other DML). When SQL calls PL/SQL a “context switch” occurs as execution moves between SQL execution and PL/SQL execution. In Oracle Database 12c Oracle has given us two tools to help reduce the impact of this context switching. The first is the ability to add a local function definition to the SELECT via the WITH clause, the second is to flag a function using PRAGMA UDF so that the compiler and optimizer will know it is to be used from SQL. Both options can measurably improve performance if used correctly.

To achieve maximum performance gains the PL/SQL function involved should not call other PL/SQL procedures and/or PL/SQL functions nor should PRAGMA UDF functions be called from “normal” PL/SQL (not inside SQL).

Trying out Jenkins

Jenkins seems to be the top code build, integration and QA automation tool to support continuous delivery.

Jenkins allows me to kick of jobs on a schedule or ofter certain events and Jenkins will keep track of the status of the jobs and the results.

To get Jenkins installed,  I read   and then read to try my first Jenkins example.

I installed Jenkins  on one of the VMs from the “landshark” demo environment for Delphix Express. Landshark consists of two Linux Centos VMs that provide source and target examples for Delphix Express. I used the “target” VM but could have just as easily used the “source” machine.

See Sharp Objects, Run with Sharp Objects, Crash with Sharp Objects – Obscure and Incorrect Error Messages in Commercial Products

January 15, 2016 Since October 2015 I have been fighting with an application programming interface (API) that works with an enterprise resource planning (ERP) system.  The API, with uses Microsoft .Net 4.0 or higher, is intended to simplify the process of automating the creation of various types of documents within the ERP system.  For example, the API […]

Adding Targets in Enterprise Manager 13c

The only thing that is constant is change.

Friday Philosophy Guest: Open Source Projects

This post is Guest Post by my friend Liron Amitzi, an Oracle Ace, presenter and instructor who specialises in Oracle design & infrastructure. You can find his blog over here.  And with that, over to you Liron :-)


I have been wondering about open source projects for a while. I’ve talked to quite a few people about it, and still don’t really understand some of it. So I decided to write a post about my thoughts regarding this issue.

I’m not going to talk (or even mention) specific projects, but it is very interesting to me how these projects run.

Color Choosing in Squarespace

Choosing colors for a new Squarespace site challenges me. There are 16+ million colors to choose from, times the number of elements in the Style Editor that I'm able to colorize. That's some scary math right there, and it helps a lot to reduce my options.

Drawing from Preexisting Artwork

Figures 1 and 2 show recent sites that I've stood up on Squarespace, and I'm pretty happy with their color schemes. Figure 1 is the "easy" case, a redesign for a cycling club's website. There was a logo in play that had been designed by a professional graphic artist. She'd done a good job in choosing colors, and all the club members were more than happy her work.

Color Choosing in Squarespace

Choosing colors for a new Squarespace site ironically is made much easier
if you find good ways to limit your options. Otherwise the 16+ million
colors from the color wheels become overwhelming....

Read the full post at

New Features of Enterprise Manager Cloud Control 13c

For those of you that have been wondering why I’ve been so quiet of recent times, it’s because my wife and I took advantage of a trip to England for UKOUG in December to spend nearly 5 weeks touring around Europe (2 weeks of which was spent river cruising from Amsterdam to Budapest with the fabulous APT river cruises, something I can HIGHLY recommend if you want to see Europe!). But while I might have been taking time off, you can bet the Enterprise Manager developers were not, with the result that Enterprise Manager Cloud Control 13c was released just before Christmas! That makes two releases in a row where Enterprise Manager is the first Oracle product to use a new major version number – EM was the first product to use the version number 12, while EM was the first product to use the version number 13!