Re: primary and foregin keys

>> it is a DB2 trick and

needs to be used with caution.
...<<

yep. One guy kept typing UNION instead of UNION ALL and complaining about poor performance...

>> Teradata got parallelism by using hashing -- one hash bucket gets
a processor and hash buckets are a partitioning enforced by mathematics. That works because the engine is doing the partitioning at the PHYSICAL level without a human being to screw it up ...<<

so does DB2, they both implement "shared nothing" approach

>> The goal of a partitioning like this is parallelism
...<<

not only. There are some tricks with different clustering indexes, such as fiction books ordered by author's last name, but non fiction ones by subject, then author's last name. That's how some public libraries store books on their shelves, and for a good reason, this clustering is best for most searches such as
- some mystery by Agatha Christie
- something on hiking in Arizona

so on
And yes, there are views and instead of triggers on top of that, so the developers don't need to know that.
What do you think? Received on Thu Dec 30 2004 - 00:59:07 CET