Performing Join problem
I have found this 'Join' query example in one of the univeristy's documents but not able to find any practicle example of that.
Could someone please help me to write the practical example of the below example:
( A WHERE restriction-on-A ) JOIN ( B WHERE restriction-on-B )
Explanation is given below:
Doing the restrictions before the join, as the transformed
version of the expression requires, is generally a good idea,
because it has the twin effects of:
(a) reducing the size of the input to the join, and hence
reducing the amount of data to be scanned in performing that
(b) reducing the size of the output from the join as well, which
could make the difference between being able to keep that output
in main memory and having to spool it out on to the disk.
Could you please tell me how can I write the query using this example.