[Info-vax] OpenVMS - DCL - Data entry filtering

[David Froble]

JF Mezei wrote:
> On 15-03-30 10:12, Stephen Hoffman wrote:
> 
>> data and accessors and logging and the rest.   You blow past what RMS 
>> can do.   You might well reach the absurdity of directly rummaging 
>> SYSUAF.DAT, as I and others have implemented. 
> 
> ALL-IN-1 provided interface to SYSUAF which was field based, independent
> of actual layout. DCL didn't. So people rummaged because of lack of API
> that could have provided field level access to those files. (and then
> allowed those files to change).
> 
> Here is a question which has always bothered me. Database systems have
> very opaque storage and indexing. (to me at least). Heck, I don't even
> know which actual files store the data, index and what not.
> 
> But if one were to compare RMS with the low level database storage in
> file(s), would the indexing and buckets etc of RMS end up competitive
> with how databases organise the data and do record searches/lookups ?
> 
> MySQL seems to have a default file organisation that appears sequential
> to me. ( so I use a different one which has indexed records where you
> specify key fields, mostly because this is what I am familiar with)
> 
> Seems to me tha a sequeintial file organsiation can't be all that
> efficient when doing database lookups by a name, or record number etc.
> It is fine when most of your lookups are wildcard searches. But not so
> much when doing simple loomup by a key such as employee number.
> 
> 
> 

Pull the entire database into memory, and you might be surprised how 
speedy it might be ....

I don't know much about the internals of any of the RDBMS products. 
I've used Microsoft SQL-2000.  In the database tables, relationships 
could be defined.  I'm guessing (really guessing here) that they are 
similar to keys.

It's my guess that when you attempt to access data using one or more of 
the relationships, the access is less work and quicker.

The more relationships, (more keys), the more work to add records (they 
call them rows) is my guess.

With today's HW and memory, the damn things appear to be very fast.