I like cake. Most people do, I suppose. And that’s why I use cake as an analogy in my classes and presentations whenever I talk about users, data, and performance.


See, there are many, many layers of cake between users and their data. Some layers are thicker than others, some more delicious, and some more important. But together the layers make the cake complete. When done correctly, these layers form something that you want to consume more and more, just like a good cake should.


You’ve been hearing a lot about AppStack this month. Truthfully whenever I hear “AppStack” I just think of cake. It makes it easier for me to understand all the layers, and I think the analogy works for others as well. Why is that? It is because AppStack means different things to different people. Just look at the previous posts and you’ll get a sense for the differing points of view about what is important.


Today I want to talk about AppStack from the database administrator’s point of view. For many people a database is a black box; Queries go in, data comes out. It’s a mystery as to what happens inside that magical box. And it’s not just a database that’s a mystery either. Admit it; you have no idea what a DBA does for work all day long. Besides a lot of Twitter and Facebook activity we are often busy providing evidence as to why the database itself is not the bottleneck in whatever business process is being seen as “acting slow”.


Let’s break this down into some delicious layers of cake:


Storage layer

The backbone of any infrastructure, your data is stored somewhere (Earthed or Cloud) on something (traditional hard drives or flash drives). Data is read from, or written to, these storage devices. Often these devices are shared among many systems, making it difficult to know if your data requests are the cause, or victim, of performance issues. All of this disk activity ultimately needs to travel through the network, too.


Server layer

It is no longer uncommon for database servers to be virtualized. Unfortunately, virtualized database servers are often improperly configured, leading to performance issues and concerns. Improper configuration choices at the host and guest layers are often the root cause for what is perceived to be a database issue. Knowing where to look (database, guest, host, storage) first is important for any administrator.


Database Layer

The database engine itself is often blamed as the source of performance issues, but the reality is that the true bottleneck exists elsewhere. In many cases, issues directly related to the database engine are caused by configuration options selected upon installation of the engine. I’ve lost track of the number of times I’ve tracked down the root cause of a database issue to be the fact that it’s so easy to click “Next, Next, Next” during an install.


User Experience

The icing on our cake is, of course, the end-user. But let’s think about what is under that icing. The end-user is interacting with an application (may or may not be local to their PC), they send a request through the network, the application takes the request and it may (or may not) need to interact with a database, and the database may (or may not) need to interact with storage, and once the data is retrieved/written, back up the chain we go.


The end-user knows nothing of the series of tubes known as the internet. And what if, at the end of all this, the end-user needs to wait for a report to be rendered? They can be sitting there, watching the hourglass turn, silently muttering under their breath about how slow the database is behaving, when in fact the issue is a piece of reporting software that takes minutes to draw a pretty graph.


And that’s why AppStack is so important to someone like me. I get the opportunity to visually show someone where the bottleneck truly lies. This saves time and reduces frustration. And in the end it makes for a more stable infrastructure for which a business is able to leverage.