I'm the webmaster for a major US university. We have a great deal of requests on our website, which I've built and been in charge of for the last 7 years or so. I've been building ever-more-complex features into our website and it's always been my practice to put as much of the programming burden on our multi-processor Microsoft SQL server as possible - using stored procedures, views, etc, and fill-in what can't be done with PHP, ASP, or Perl from the IIS web server. Both servers are very powerful and capable machines. Since I've been doing this alone for so long without anyone else to brainstorm with, I'm curious if my approach is ideal for even higher load situations we'll have in the future.
My question is: Is it better practice to place more of the load burden on the SQL server using nested SELECT statements, views, stored procedures and aggregate functions, or should I be pulling multiple simpler queries and processing through them using server-side compile-time scripts like PHP? Keep on keepin' on or come up with a better way?
I've recently become more interested in performance after I did some load traces and learned just how much I've been putting on the shoulders of the SQL server. Both the web server and SQL servers are fast and responsive throughout the day, and almost without regard for how much I put on them, but I'd like to be ready and have trained myself and upgraded my existing code optimized best practices in mind by the time it becomes important.
Thanks for your advice and input.
You put each layer in your stack to use in the domain it fits best.
There is no use in having your database server send 1000 rows and using PHP to filter them if a WHERE-clause or GROUP-clause would suffice. It's not optimal to call the database to add two integers (SELECT 5+9 works fine, but php can do it itself, and you save the roundtrip).
You will probably want to look into scalability: what parts of your application can be divided unto multiple processes? If you're still just using 2 layers (script & db), there is a lot of room for scaling there. But always start with the bottleneck first.
Some examples: host static contents on CDN, use caching for your pages, read about nginx and memcached, use nosql (mongoDB), consider sharding, consider replication.