Subject Re: [ib-support] Re: Generating UniqueID [2]
Author Ann W. Harrison
I wrote:

> >The GUID algorithm that I am familiar with changes the first byte
> >for each new id, greatly reducing the effect of prefix compression.
> >Less compression -> longer keys -> fewer keys per page -> deeper
> >indexes -> worse performance.

At 01:40 AM 11/10/2001 +0000, zifnabbe@... wrote:

>How can this performance be compared over a NUMERIC(18,0)?

If in fact the first byte of the GUID changes most frequently,
you'll tend to have compressed key lengths > 10, meaning that
the index will be about twice as wide.

>Is it a drastic performance hit? Or can we assume that a benefit of a GUID
>overrules the performance hit?

That's certainly application specific.

>But thinking further... If we create the GUID on the interbase
>server, then the only difference in the number is the time value.

Actually the GUID is more complicated than that and includes a
simple counter (I think) that avoids problems of simultaneous


We have answers.