July 2017

Redo OP Codes:

This posting was prompted by a tweet from Kamil Stawiarski in response to a question about how he’d discovered the meaning of Redo Op Codes 5.1 and 11.6 – and credited me and Julian Dyke with “the hardest part”.

Over the years I’ve accumulated (from Julian Dyke, or odd MoS notes, etc.) and let dribble out the occasional interpretation of a few op codes – typically in response to a question on the OTN database forum or the Oracle-L listserver, and sometimes as a throwaway comment in a blog post, but I’ve never published the full set of codes that I’ve acquired (or guessed) to date.

When UPDATE becomes an INSERT

During a research for VOODOO, we came across a lot of interesting stuff inside REDO.
One of my favourites is an UPDATE, becoming an INSERT </p />
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When UPDATE becomes an INSERT

During a research for VOODOO, we came across a lot of interesting stuff inside REDO.
One of my favourites is an UPDATE, becoming an INSERT </p />
</p></div>

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Fast Now, Fast Later

The following is the text of an article I published in the UKOUG magazine several years ago (2010), but I came across it recently while writing up some notes for a presentation and thought it would be worth repeating here.

Fast Now, Fast Later

The title of this piece came from a presentation by Cary Millsap and captures an important point about trouble-shooting as a very memorable aphorism. Your solution to a problem may look good for you right now but is it a solution that will still be appropriate when the database has grown in volume and has more users.

I was actually prompted to write this article by a question on the OTN database forum that demonstrated the need for the basic combination of problem solving and forward planning. Someone had a problem with a fairly sudden change in performance of his system from November to December, and he had some samples from trace files and Statspack of a particular query that demonstrated the problem.

Quick tip–database link passwords

If you are relying on database links in your application, think carefully about how you want to manage the accounts that you connect with, in particular, when it comes to password expiry.

With a standard connect request to the database, if your password is going to expire soon, you will get some feedback on this:



SQL> conn demo/demo@np12
ERROR:
ORA-28002: the password will expire within 6 days


Connected.


But when using those same credentials via a database link, you will not get any warning, so when that password expires…you might be dead in the water.

In Memoriam – 2

This is the second of two items that my mother typed out more than 25 years ago. I had very mixed emotions when reading it but ultimately I felt that it was a reminder that, despite all the nasty incidents and stupid behaviour hyped up by the press and news outlets, people and organisations are generally kinder, gentler and more understanding than they were 60 years ago.

This story is about the birth of my brother who was born with a genetic flaw now known as Trisomy 21 though formerly known as Down’s syndrome or (colloquially, and no longer acceptably) mongolism. It is the latter term that my mother uses as it was the common term at the time of birth and at the time she typed her story.

Words I Don’t Use, Part 1: “Methodology”

Today, I will begin a brief sequence of blog posts that I’ll call “Words I Don’t Use.” I hope you’ll have some fun with it, and maybe find a thought or two worth considering.

The first word I’ll discuss is methodology. Yes. I made a shirt about it.

Chinese support added to parts of the plsql random data generator

For quite a while I have been wanting to add Chinese support to some of the dbms_random functions, and this
last weekend I finally got some time to work a little bit on it. So now the library support Chinese output in functions in the
core_random package, text_random package and location_random package.

12.2 New Feature: the FLEX ASM disk group part 3

In the previous 2 parts of this mini series I introduced the Flex ASM disk group and two related concepts, the Quota Group and File Group. In what should have become the final part (but isn’t) I am interested in checking whether quotas are enforced.

(Un)fortunately I have uncovered a few more things that are worth investigating and blogging about, which is why a) this isn’t the last post and b) it got a bit shorter than the previous two. Had I combined part 3 and 4 it would have been too long for sure … BTW, you can navigate all posts using the links at the very bottom of the page.

Are quotas enforced?

The purpose of the Quota Group is … to enforce quotas on a disk group, much like on a file system. This is quite interesting, because you now have a hard limit to which databases can grow within a disk group even for non-CDBs.

The $50 Million Hyphen

There are a plethora of mishaps in the early space program to prove the need for DevOps, but Fifty-five years ago this month, there was one in particular that is often used as an example for all.  This simple human error almost ended the whole American space program and it serves as a strong example of why DevOps is essential as agile speeds up the development cycle.