Re: Oracle RDB on VAX/Open MVS

We had to migrate AARPs Rdb database to Oracle awhile back.

We had a bit of an advantage since we sell an Rdb tuning
analysis/monitoring tool (DBTune). We were able to take pieces of that
code and write a Q&D program that extracted the Rdb structure, and then
generate the SQL for a fairly compatible Oracle structure ( it still
neeed a bit of hand work to take off the rough edges but was far better
than doing it all "by hand")...then used Rdb's rmu/unload to generate
input to SQL Loader on Oracle. Biggest ( or at least the most
annoying) stumbling blocks we found were

1) Rdb date fields all need editing to get an Oracle Rdb date
acceptable format ( OpenVMS dates carry more precision that Oracle can
accept). Either edit the unloader text itself using automated scripts,
or add a computed column to generate the right format for every date
field.

2) Segmented strings need to be written out by customized progsrams
rather than rmu/unload, then use SQL Loader. The two database store
these long strings TOTALLY differently.

3) A field declared in Rdb as a number like xx.yy, may unload as
xx.yyy, but not always...I leave it up to those "in the know" to figure
out why. We just had to "adjust" the field declarations accordingly.

4) Stored procedures and triggers are going to take some recoding. The
SQL is in the "ballpark", but will need handwork to get it in Oracle
acceptable format.

I know there were a few tools that could help perform much of this type
of migration back in the 1980s, but they are long gone now or no longer
support Rdb. A pity since on OpenVMS, Rdb will still drive Oracle into
the ground. Rdb is written specifically for OpenVMS, Oracle had to make
"consessions" in order to maintain a single code base (as much as
possible) across multiple platforms. It shows in the relative
performance.

Have you thought of using a Charon Vax emulator on PC style hardware
rather than going to Linux/Oracle? We have a customer who took that
approach and it has been working out quite well for them. The avoided
all the cost of the database migrations, and al the recoding of support
apps. Plus, they did not have to "retrain" everyone, or wait for them
to come "up to speed" on a totally different database system ( say
about 12 months of work minimum) which was another "hidden" cost of
switching to Oracle.

There is also an Alpha emulator that has been announced that can run on
PC style hardware, but it is only out as an evaluation right now.

Keep in mind that there is "PC" hardware (like on your desktop), and
"PC" hardware like a 4 processor, 8Gb, fiber based server with hardware
RAID. In short, the emulators "ain't nothing to sneeze at" on the right
platform.

And there is always the I64 option to stay with OpenVMS/Rdb directly.
We have the "smallest" Itanium deveopment system and it blows away our
Alpha 2100/2100A systems development systems.

Dr. Robert Young, ALI Database Consultants

.

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