Chapter 2. Inside the Black Box: Engine Architecture

Database administrators need an understanding of all of the factors that affect their systems. This includes appropriate operating system information, general information about Informix OnLine or IDS internal operations, and specific information regarding the individual site's setup.

This basic knowledge prepares the DBA for effectively managing the operations of an OnLine or IDS database. These items can be considered the prerequisites for becoming an effective DBA.

The actual day-to-day operations of Informix databases are straightforward and relatively simple. Keep the system up. Make backups. Kill a few runaway jobs occasionally. When things are going smoothly, anyone can be the DBA. For the most part, the engine is a reliable black box. You make requests of it. It gives you back data.

It's when things start to go wrong that the DBA needs to understand what's really going on inside the black box. When the system crashes, nobody wants to be the DBA. If you survive the encounter with angry users who've had the database blow up in the middle of THE MOST IMPORTANT JOB THEY'VE EVER RUN, you'll have to answer to management types who want to know what went wrong with the system and who to hang for doing it. Unless you are able to get inside the database and avoid the crash in the first place, or at least be able explain what happened, you'll be the most likely candidate for the lynch mob's noose.

I'm making a distinction between understanding the architecture of the database and understanding the data flow. Actually, these two areas of knowledge are so closely associated that they are effectively the same skill set. To understand how the data is managed within Informix, one has to understand the architectural entities that manage this flow. Similarly, to understand the architectural entities, you must know how they are used, what they are used for, and how the data flows through the database architecture.