My experience on several terabytes DBs has been opposite, I hope you trust me too :-D .
Getting a list of categories, then you click on a catagory and get a list of products, then you click on a product and get a list of components is much faster and less stress on a db(and therfore not only each querry is faster but more scaleable); it reduces a # of joins.
Ex: A common thing I used to consult on before Java was Performance and Tuning SQL DBs. A client would have a slow querry, and they say make it fast. I can! I used to take things that take 15 minutes down to split second. One tecquique is to break a complex querry into 2 simpler querries with less joins; even using a temporary tables. This exponentialy increased peformance to sub second.
(also.. you avoid group by, distinct, order by... imagine sorting 30 million records BEFORE you start to returun... and that you have 10,000 concurent users each runing a variation on the querry. Lots of trick to get arround that).
All the best,
.V
Clinton Begin wrote:
With the N+1 selects solution, you can do this with one query, with one hit to the database -- no matter how many relationships you have or how much data.
Trust me bud, this is VERY good advice.
Cheers, Clinton
