Architecture

A couple of weeks ago I was making my way through the office. As I came towards the end of the large, open-plan room I became aware that there was someone following behind me so, on passing through the door I held it briefly for the person behind me {there was no where else they could be going}, turned left and through the next door – and again held it and this time looked behind me to see if the person was still going the same way as I. The lady behind gave me the strangest look.

The strange look was reasonable – the door I’d just held for her was the one into the gentleman’s bathroom. *sigh*

This blog post is an introduction to a few posts that can be grouped together under the banner of 'System Architecture'. Specifically, I'm referring here to Oracle Database System Architecture, not system architecture in general nor 'Oracle architecture' in general, which is an ever-growing beast. In this series of posts, I will take at look [...]

I just wanted to put up a post about DBMS_APPLICATION_INFO. This is a fantastic little built-in PL/SQL package that Oracle has provided since Oracle 8 to allow you to instrument your code. i.e record what it is doing. I’m a big fan of DBMS_APPLICATION_INFO and have used it several times to help identify where in an application time is being spent and how that pattern of time has altered.

Some PL/SQL developers use it and some don’t. It seems to me that it’s use comes down to where you work, as most PL/SQL developers are aware of it – but not everyone uses it (a friend of mine made the comment recently that “all good PL/SQL developers use it“. I can understand his point but don’t 100% agree).

We've just booked the first European venue for the Understanding Storage Masterclass. I will be presenting the Masterclass on April 24/25 2012 at Prospero House in London, tickets are available HERE. I'm pretty excited to host this training session in my home country, and I hope to see you there!

For about 12 months now I’ve been saying to people(*) that I think the single box server is going to make a comeback and nearly all businesses won’t need the awful complexity that comes with the current clustered/exadata/RAC/SAN solutions.

Now, this blog post is more a line-in-the-sand and not a well researched or even thought out white paper – so forgive me the obvious mistakes that everyone makes when they make a first draft of their argument and before they check their basic facts, it’s the principle that I want to lay down.

Something I’ve just reminded myself of is that under Oracle you cannot add a comment on an index or a constraint. You can only add comments on tables, views, materialized views, columns of those object types and a couple of esoteric things like Operators, Editions and Indextypes.

Here is an example of adding comments to tables and columns:

This is a post about the importance of appropriately simplistic architectures. I frequently get involved with the creation of full-stack architectures, and in particular the architecture of the database platform. There are some golden rules when designing such systems, but one of the most important ones is to keep the design as simple as possible. [...]

<..IOT1 – the basics
<….IOT2 – Examples and proofs
<……IOT3 – Significantly reducing IO
<……..IOT4 – Boosting Buffer Cache efficiency
<……….IOT5 – Primary Key Drawback
<…………IOT6(A) – Bulk Insert slowed down

In my last post, IOT part 6, inserts and updates slowed down, I made the point that IOT insert performance on a relatively small Oracle system was very slow, much slower than on a larger system I had used for professional testing. A major contributing factor was that the insert was working on the whole of the IOT as data was created. The block buffer cache was not large enough to hold the whole working set (in this case the whole IOT) once it grew beyond a certain size. Once it no longer fitted in memory, Oracle had to push blocks out of the cache and then read them back in next time they were needed, resulting in escalating physical IO.

<..IOT1 – the basics
<….IOT2 – Examples and proofs
<……IOT3 – Significantly reducing IO
<……..IOT4 – Boosting Buffer Cache efficiency
<……….IOT5 – Primary Key Drawback
…………>IOT6(B) – OLTP Inserts