Feeds

Multivalue datatypes

What a lot of people like repeating groups...

5 things you didn’t know about cloud backup

Editors blog Mark Whitehorn's recent article on multivalue data types in Access (here) sure attracted some comments.

No, multivalue fields (non-atomic fields or repeating groups as I think I remember them) are not new. I didn't like them when I was an IMS DBA back in the eighties - and I met most of the arguments in favour of them back then. But, whatever Oracle does, they aren't part of a "proper" relational database.

To set the matter straight and to avoid unnecessary email traffic:

  • Yes, we have heard of Dick Pick;
  • yes, we do realise that multivalued datatypes can sometimes be used safely if you're careful; or your DBMS is (a bit like GoTos, and with similar caveats);
  • yes, we do realise that databases like U2, ADABAS etc have their uses and that Cache is actually a very interesting database, which is much more than just a modern implementation of Pick or Mumps...

However, I still think that Relational Theory (as in Codd's ACM paper) is a "good thing" and that it simplifies the delivery of reliable, resilient systems in the "real world"; and that XML columns, fields containing sets, Blobs and similar modern non-relational additions, while expedient, re-introduce some of the issues which lead to IMS (which I know very well), say, being replaced with DB/2 or other RDBMSs - in general.

And, FWIW, I do also realise that IMS, as well as IDMS, CA Datacom and other legacy databases are still in active use, because the benefits from keeping them (and, as well as the simple replacement and regression-testing costs, there are sometimes resource/performance benefits from using unnormalised data for specific access opaths; there are also consequences) outweigh the possible benefits from replacing them.

A longer article justifying these positions in detail will take a little time to prepare - but watch this space...®

Boost IT visibility and business value

More from The Register

next story
Why has the web gone to hell? Market chaos and HUMAN NATURE
Tim Berners-Lee isn't happy, but we should be
Linux turns 23 and Linus Torvalds celebrates as only he can
No, not with swearing, but by controlling the release cycle
Apple promises to lift Curse of the Drained iPhone 5 Battery
Have you tried turning it off and...? Never mind, here's a replacement
Sin COS to tan Windows? Chinese operating system to debut in autumn – report
Development alliance working on desktop, mobe software
Eat up Martha! Microsoft slings handwriting recog into OneNote on Android
Freehand input on non-Windows kit for the first time
Linux kernel devs made to finger their dongles before contributing code
Two-factor auth enabled for Kernel.org repositories
This is how I set about making a fortune with my own startup
Would you leave your well-paid job to chase your dream?
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Endpoint data privacy in the cloud is easier than you think
Innovations in encryption and storage resolve issues of data privacy and key requirements for companies to look for in a solution.
Scale data protection with your virtual environment
To scale at the rate of virtualization growth, data protection solutions need to adopt new capabilities and simplify current features.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?