2008/11/5 Andy Freeman <[EMAIL PROTECTED]> > > As a programmer, you have two choices, you can either put things > together so they can be accessed at the same time or you can do some > processing to combine multiple pieces of data. Since the latter is > exactly what SQL joins do....
Definitely. And SQL does it internally, creating and taking advantage of design optimisations within the database application which came about after millions of dollars and/or many hundreds of thousands of man hours spent by the top people in the specialisation. GQL doesn't appear give you that, at least as far as joins are concerned, it gives you a list and leaves it to a general-purpose programmer to do it by hand firing db requests at a server farm time after time. I'm not knocking GQL, it is what it is, but looping around in Python asking for crumbs of data doesn't really compare with the efficiency of a dedicated db application > > > > If you > > wanted to find out how many DVDs were never rented from a video rental > > service over the last year, you'd have more than 1000 titles and even if > you > > didn't, you'd have to try to match them all up with all the rentals one > at a > > time. > > Why? If each dvd has a unique key and a last rental time, it's > trivial to write a query that will find the ones that weren't rented > last year. If the last rental was yesterday, how does that help me work out if it was rented in 2007? Or October to October. > > 10 million records at 100 bytes/record is 1 billion bytes. That > doesn't happen in "a moment or two". You're obviously not used to British understatement. :-) Cheers, Ian --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~----------~----~----~----~------~----~------~--~---
