bill grefe <[log in to unmask]> wrote:

>Changing the main key will only help if the dataset is reloaded.  Which begs
>the question, how many systems reload datasets? How many? How often? Is it
>worth it?
>
>Bill Grefe
>[log in to unmask]
>

Assuming that "main key" is another name for "primary path", then it can help
alot.  Chose the "proper" primary path, and then use a tool such as Adager's
DETPACK to pack along that path.  The primary path should be one that is
accessed the most, but also one that averages more than one entry per chain.

One word of caution: It is possible for applications to be written poorly, such
that they depend on a specific path being the primary path.  If you change the
primary path to another path, that application will break.  That is one of the
reasons that Adager allows you to pack along a non-primary path, without
changing which path is primary.

I have found that the ratio of database size to physical memory is typically
bigger today than 20 years ago, making data locality an even bigger issue
today.

Steve Cooper