Re: How to determine database market share?
Date: Sat, 5 Nov 2005 09:40:09 -0700
"hpuxrac" <johnbhurley_at_sbcglobal.net> wrote in message
># Meanwhile most relational databases, particularly Oracle, become less
> # relational with each release. Codd defined relational as the extent
> to which
> # the user of the data (via DML) is isolated from the way the data is
> # physically stored. Some of these things are to improve performance
> # hints in Oracle) or to improve concurrency (WITH UR in DB2) but they
> # decidedly not relational in nature.
> Um I guess I would agree (maybe somewhat) with only your first sentence
> Starting with the second sentence you are not exactly close.
> The relational model says nothing about physical storage.
> The relational model says nothing about hints in SQL statements.
> The relational model says nothing about concurrency.
> Each vendor has developed proprietary technology to improve the
> performance of their products agreed.
> But arguing that these parts of the technology stray from a relational
> model when the model doesn't say anything about them is not good logic.
I did not mean "physical storage" as in disk drives, but rather the way the data is physically stored in columns, tables and indexes, etc. Physical disk storage could be an issue, but even most modern non-relational databases do not require the data access language to know about the disk storage.
Regarding the "relational model, I am talking about the definition developed by Codd who invented the relational model. Hints and syntax to improve concurrency did not even exist back when Codd developed the relational model, so it is ridiculous to say that the relational model does not say anything specifically about them. I absolutely guarantee that Codd would puke all over hints and many of the other Oracle proprietary enhancements because he considers them non-relational (to the extent they are used).
Even in the mid 1980's when Codd ranked databases to the extent they were "relational," Oracle did not rank very high (way before they came up with most of their current proprietary enhancements). My guess is that you don't know who Codd is and never read any of his writings (he has been dead for a number of years now).
The OP seemed to say that IBM non-relational databases like IMS should not be counted in the database market share numbers. If so-called relational databases are no longer as relational as they once were, then the distinction becomes less meaningful. Personally, I have nothing against hints, other Oracle proprietary enhancements, or even IMS if one accurately determines that they are necessary to achieve the desired results. Received on Sat Nov 05 2005 - 17:40:09 CET