What is it?
Not for the first time, Oracle has created poor publicity for a new release of its market-leading database, by aggressively over-egging its forecasts of take-up. Earlier this year, Pythian group, which manages databases remotely for Oracle customers, reported that only three of more than 700 production databases it looks after had moved to Oracle's latest version, 11g. But that's not unexpected for a product that was only released last year.
A better guide may be the 35% of International Oracle User Group members who told their organisation they intended to make the move within the next year - although the worsening financial climate may reduce this. The previous version, Oracle 10g, is likely to hold sway for a few years yet.
Oracle certification is the most expensive to achieve of the three leading mid-market databases - IBM's DB2 being cheapest. But Oracle skills carry a salary premium, while Microsoft's SQL Server is the lowest paid of the three.
Where did it originate?
Oracle was released in 1979 by Larry Ellison's Relational Software Inc. It didn't support transactions, but Ellison was able to claim he'd beaten IBM into the market with an SQL database.
This was the earliest of a series of much-hyped "firsts" for the company, which changed its name to Oracle Corporation in 1982. Oracle 10g, the currently dominant version, began shipping in 2004.
What is it for?
Oracle developers have a choice of PL/SQL, Oracle's SQL implementation, using Oracle Reports or Oracle Forms or Java, using Oracle JDeveloper. There's also the GUI-based Oracle SQL Developer, part of Oracle's drive to simplify development and open it up to non-professionals. Java is the fastest growing development environment, but Oracle has pledged to support Forms and Reports through to 2013.
The most widely used version is the Enterprise Edition, but there's also a Standard Edition for between one and four CPUs, a Personal Edition with all the functionality of the Enterprise Edition, and the free, downloadable Express Edition, which comes with many constraints - one database per machine, one CPU, 4GB data maximum.
What makes it special?
Oracle has made much of the "green" credentials of 11g -which actually translates into lower data centre costs, such as a three-fold reduction in disc space using compression. 11g also makes use of the standby database - which normally waits in reserve in case of a system crash - to take on workloads such as reporting, backup, testing, and rolling upgrades of production databases.
How difficult is it to master?
It's not cheap, and fairly time consuming, if you take the classroom route: five days to learn PL/SQL for example - and that follows a five-day course introducing you to SQL on 10g. Java developers with J2EE application server experience can be productive more quickly.
Where is it used?
Oracle has the broadest customer base of all database vendors, though it runs up against niche competitors such as Sybase in investment banking and mobile databases, and Teradata in high-end data warehousing.
What systems does it run on?
Oracle has focused on Linux in recent years, and so far 11g is available only on Linux and Windows. 10g is also supplied for IBM's zSeries and several flavours of Unix, including IBM's AIX, HP UX and Sun Solaris.