9. Miscellaneous

9.1 What's the difference between SE and IDS/ODS?

In general, SE performs slower than IDS, supports fewer data types, and lacks many of the features of its larger sibling. Specifically speaking, Informix-SE has the following differences:

• No support for BLOBs (Binary Large Objects)
• No support for the VARCHAR data type
• No support for the TEXT data type
• No support for the BYTE data type
• ESQL/C is not multi-threaded
• ESQL/C does not support TP/XA
• TERMINFO is not supported on Linux

Don't make the mistake, however, of thinking that this means you should ignore SE. Informix-SE is a wash-and-wear RDBMS because it is so simple to administer. Install it, make a couple of one-line edits to some configuration files, and you are off to the database races. SE will will just keep going and going and going and... This feature should appeal to those sites that lack a full-time MIS administrator. SE also shines when the applications banging on it don't demand breakneck performance; although not sluggish, it is not the speed-demon that some of its competitors are. Again, the trade-off is performance for robustness and ease of administration and maintenance.

9.2 What's the current release?

As of the date this FAQ was last updated, the most current release level is Informix-SE 7.24.UC5, released 13 July 1998. The code base, however, has been forked for the glibc release, and it is dated 14 October 1998.

9.3 What's the difference between sqlexec and sqlexecd?

The sqlexec program is the database engine, creating and manipulating databases. Each program that accesses a databases gets its own copy of sqlexec (which explains why killing sqlexec is such a bad idea). The host OS handles the locking necessary for resource management between multiple SE processes.

In contrast, sqlexecd never touches the database. It's raison d'etre is listening for requests for database access (usually originating from remote applications/clients) and starting a sqlexec process to communicate with the requesting client and twiddle the database as required.

This relationship is analogous to the difference between rlogind, which waits for a machine to try to login to a system, and the shell that rlogind executes to communicate with the user.

9.4 Is Informix-SE "thread-safe?"

Although the question is a good one, it doesn't matter. SE is a single-threaded, synchronous application dealing with a single request at a time. Hence, threading doesn't really have any bearing on how the engine behaves.

9.5 Will Informix-SE run on a multi-processor machine?

Yes, because the underlying OS will handle MP issues. On the other hand, if you are asking, "Will Informix-SE take advantage of multiple processors?" then the answer is "No." SE, being single-threaded, does not in itself benefit from multiple processors.

9.6 Is ESQL/C "thread-safe?"

Yes and no. The libc5-based version is not thread-safe because libc5 is not thread-safe, which was one of the motives behind glibc/libc6. Jonathan Leffler also pointed out the ESQL/C only works with DCE threads, while Linux (most likely) only supports POSIX threads. Although these two thread incarnations are similar, they are incompatible.

Until someone corrects me, I will assert that the glibc-based version is thread-safe because the C-library used to compile the engine is thread-safe.

9.7 How do I get involved?

Write documentation

If you would like to get involved with Informix on Linux, Tom Schaefer netd@mindspring.com coordinates the effort to get HOWTOs and related documentation written and distributed to the appropriate repositories. A special need exists for HOWTOs on these topics:

• ODBC Connectivity
• JDBC Connectivity
• Perl, DBD and DBI

Beta Testing

As other products approach formal release, Informix will need beta testers. Art Kagel coordinates the beta program. For further information, contact him at kagel@erols.com. Include at least the following information so that Informix can match the product being tested to your level of Informix experience and the platform on which you would be testing the product:

• Linux distribution and version
• Size of potential test database
• Complexity and type of test application
• Type of hardware (uni-, dual- or multi-CPU)
• Tape archive device
• General level of experience
• Specific Informix products you want to test

Join IIUG

The International Informix Users Group was instrumental in persuading Informix to release Linux versions of their products. The Advocacy Committee continues these efforts. Currently, joining IIUG doesn't cost a dime, and you get the opportunity to have influence with Informix as well as to interact with other people using Informix and Informix on Linux. Check them out at http://www.iiug.org on the web.

Write to Informix

You can always write directly to Informix and tell them what specific Informix product you would like to see ported to the Linux environment. They do listen.

9.8 What does "SE" stand for?

Standard Engine. Informix-SE is an ISAM-based database engine that lives on cooked, that is, formatted, filesystems.

9.9 Interesting Trivia

For those interested in such trivia, Carlton Doe reported that in the first few days following Informix's announcement, downloads from the Intraware site initially hit about 700 per day. They have since leveled off to about 300/day. Informix has not yet released information about sales of runtime licenses or support contracts.

A similar program for Microsoft Windows NT was announced at the same time as the Linux Developer Bundle. At least initially, Linux downloads out-paced NT downloads ;-).