2011/5/5 Matt Robinson <m...@lazycat.org>: > On 4 May 2011, at 23:57, Michał Piotrowski wrote: > >> 2011/5/4 Marco Pivetta <ocram...@gmail.com>: >>> SQL is way faster than PHP processing. I would really go for a filtered >>> join. That's what SQL is there for :) >>> Just be sure to filter by index and to return a limited resultset. >>> >>> Sequential scan in PHP has to be ABSOLUTELY avoided :) >> >> I'm not sure how to do this if I need a multiple dynamically added >> conditions. > > SQL (certainly in mySQL) supports conditionals in queries, so if the data you > use to make the choice is in the database, you can do it all in the query. > > Another way to approach your problem is to have your web app trigger events > when certain actions occur - this way you're approaching issues like "have > already been purchased by at least one of his friends" from the other end. > When someone buys a product, add it to each friend's recommendation list. > Then your look-up query is much more simple. You can even queue these events > up and process them later, since it's usually not vital that such information > is "live". > > As an aside: typically very complex queries like this are done by background > processes only periodically (e.g. every few hours) and stored in look-up > tables or similar. Particularly as you start getting many users, complex > queries quickly become a bottleneck, so you produce them offline beforehand > and store them in a way that's simple and quick to fetch by your site's PHP > scripts (in a simple cache table or object store). You never want a simple > request page to be doing so much heavy lifting that it'll slow down and > prevent you scaling later. If the heavy processing stuff is split off into a > separate process, you can also move that process to another server later.
Thanks for your know-how! > > > -- Matt > > -- > If you want to report a vulnerability issue on symfony, please send it to > security at symfony-project.com > > You received this message because you are subscribed to the Google > Groups "symfony users" group. > To post to this group, send email to symfony-users@googlegroups.com > To unsubscribe from this group, send email to > symfony-users+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/symfony-users?hl=en > -- Best regards, Michal http://eventhorizon.pl/ -- If you want to report a vulnerability issue on symfony, please send it to security at symfony-project.com You received this message because you are subscribed to the Google Groups "symfony users" group. To post to this group, send email to symfony-users@googlegroups.com To unsubscribe from this group, send email to symfony-users+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/symfony-users?hl=en
