While investigating tools for generating ER Diagrams for the data warehouse I’m working on I came across this good article on databasejournal.com which compares three of the top CASE (computer aided software engineering) tools for Oracle.

In the article Steve Callan quickly highlights the differences between Microsoft Visio 2003, Oracle Designer and AllFusion ERwin Data Modeler.

What can we take home from this article? Well, Microsoft Visio is (relatively) cheap at $499 and has good reverse engineering abilities, but won’t write database creation code for you.

Oracle Designer is clumsy, but since it’s bundled with Internet Developer Suite you might already own it; otherwise you’re probably not likely to justify the $5,000 cost of entry.

ERwin really seems like the Cadillac solution for database modeling. The $3,995 price tag will put off most, but like they say in the auto industry, if you’re worried about gas mileage you’re not ready for a Cadillac.

Check out the full article for details. Also check out the Oracle section at DatabseJournal.com for some nice series on Oracle related topics.

oracle, database, rdbms, dbms, oracle database, database management, database design, dba, database administration, er diagramming, case, software engineering

From the Oracle Application Server Installation Guide, 10g Release 2 for Linux Part I topic 4.8:

Typically, the computer on which you want to install Oracle Application Server is connected to the network

Typically? I mean, I know you want to write documentation for the broadest case possible, but it seems just a little unlikely that you would have an application server which would not be connected to a network.

Go ahead; correct me if I’m wrong.

oracle, oracle application server, humor, irony, documentation, tech writing

A recent comment on my story about converting UNIX timestamps to Oracle dates prompted me to do a little extra digging on UNIX time.

UNIX time is a standard system used not only in UNIX but in many other modern computer systems. Instead of being divided into years, months, hours, minutes, etc. UNIX time is simply a number which represents the number of seconds which have passed since midnight Coordinated Universal time (UTC, the same time zone as Greenwich Mean Time, sometimes referred to as Zulu time), January 1, 1970. This date is often referred to as the UNIX epoch.

Sound like a lot of seconds? It is. At the time of this writing it has been 1,145,404,660 since the UNIX epoch, but since people like to think of dates the old fashioned way, in years, months, days, hours, minutes and seconds the computer is almost always nice enough to convert the UNIX time into the familiar date and time format, and to your local time zone.

One of the strengths of UNIX time is that when it is recorded (a point in UNIX time is typically referred to as a UNIX timestamp) it is always relative to Greenwich Mean Time. That means UNIX timestamps can be easily converted to different time zones with no ambiguity.

For all the gruesome details on UNIX time, Wikipedia has a typically thorough article on the topic.

While there are several sites on the web to convert a UNIX timestamp to human readable format and vice-verse be careful. Many sites will do the conversion based on their time zone. 4WebHelp.net provides a great page for converting both ways.

In contrast to UNIX time, Oracle Databases record time in a more traditional year, month, day, hour, minute, second manner. In order to convert Oracle dates to a different time zone you need to know what time zone the date was originally recorded in. Only recently has Oracle introduced a time datatype with a time zone attribute.

unix, time, timestamp, time zone, date, oracle, database, solaris, linux

After having to do this several times in the past few weeks I have updated my directions on managing secure certificates in OAS to include importing a renewed OAS certificate.

application administration, oas, oracle application server, sysadmin, system administration, oracle

Over at the ITToolbox blogs there’s a great entry on the Oracle shared pool advisory in 9iR2. This type of article is great as it presents a tool, describes it, and walks you right through applying the knowledge.

Here’s their description of the advisory:

The shared pool advisory is an Oracle9i feature that keeps track of the library cache’s use of shared pool memory. While doing this it keeps statistics to determine the behavior of differently sized shared pools. Typically, the advisory will keep a bucket of statistics for shared pool sizes that range from 50% below your current setting to 200% of your current setting. It is then up to us as database administrators to use these statistics to determine what the size of the shared pool should be through the use of the view V$SHARED_POOL_ADVICE.

Check out the article for more information on how to enable and use the advisory.

oracle, oracle database, dba, dbms, oracle dbms, database tuning, database administration

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