Re: Can joins be less efficient?

Actually, in some cases where you have large tables (think DW with 100s of Millions of rows) the join is sometimes more costly than the code you are mentioning here. Depends on partitioning/indexing/cpus/optimizer/etc....

-Vikas

"NoSpam" <NoSpam_at_NoSpam.com> wrote in message news:<a2pj0t$sdh$1_at_ih292.ea.unisys.com>...
> I'm working on the code written by somebody else. What this code does is
> that it makes a query to the DB to obtain a resultset. Then from each row of
> the resultset, it repeatedly makes a second query to obtain a second
> resultset by using the key field in the first as a key to the second. It is
> very obvious that the two queries can be combined with a simple join. But
> this person insisted that there are times that cascaded reading of the
> resultsets can be faster than a simple join but he couldn't give me an
> example. I just wonder if it really can be true and under what circumstances
> that reading two resultsets can be faster than a single resultset with a
> join when a common key field exists in both tables.
>
> TIA
Received on Thu Jan 24 2002 - 18:58:08 CST