OK, Arnon, now you have to change all your SQLA code to compare id's instead of objects. Bummer.
On Friday, May 3, 2013 3:24:22 PM UTC-4, Derek wrote: > > Let's take a look at identity comparison vs integer comparison... > import timeit > setup = """ > def isequalItems(itemone, itemtwo): > return itemone is itemtwo > > def isequalInts(itemone, itemtwo): > return itemone == itemtwo > > def testOne(): > a = 1 > b = 2 > isequalItems(a,b) > > def testTwo(): > a = 1 > b = 2 > isequalInts(a,b) > > """ > print "isequalitems", timeit.timeit(stmt="testOne()", setup=setup, > number=10000000) > print "isequalints", timeit.timeit(stmt="testTwo()", setup=setup, > number=10000000) > > I get > isequalitems 2.77487170111 > isequalints 2.73482146489 > > So, integer comparison is faster. This is with Python 2.7. > PyPy 1.9... > isequalitems 0.067024457849 > isequalints 0.0263884617855 > > Integer comparison is still faster. > > On Friday, May 3, 2013 10:36:10 AM UTC-7, Anthony wrote: >> >> >> RDBMS are built for complex filtering - this is (part) of what SQL is >>> allabout - I wouldn't want to dismiss that - it would be a bad choice >>> all-around. >>> >> >> A complex filter on a small set of items might be faster in Python than >> doing another database hit. And a simple filter might belong in the db if >> it has to go over lots of records. As I said, these are orthogonal >> considerations. >> >> >>> Conversely, simple-filtering is way too verbose using the DAL - it's an >>> overkill for that, and makes the code much less readable. >>> >> >> Don't know why you think that. >> >> >>> For simple filtering, well, I'd rather do it in python and get >>> readability, becuase the performance-benefits are negligible. >>> >> >> But I thought you were a fan of achieving negligible performance benefits >> at great cost (see below). >> >> >>> Now you've really lost me -- what does any of this have to do with RDBMS >>>> vs. NoSQL? And why shouldn't you do complex filtering in Python? >>>> >>> >>> See above. >>> >> >> Still don't know why you would want a NoSQL database or what it has to do >> with this topic. >> >> >>> db.Country(france).select().find(lambda r: r.Language != spanish and r. >>>> Population > 1000000) >>>> >>> >>> That's actully pretty nice - I didn't know I can do that - but what >>> would the "france" and "spanish" objects be in this case? Ids? >>> >> >> Well, you've sure made a lot of claims about what web2py needs without >> knowing much about what it already has. Those are ids. If they were rows, >> then you would just do france.id and spanish.id. >> >> >>> OK, please provide some benchmarks. What percentage decrease in CPU >>>> usage can we expect if we compare object identities rather than integer >>>> equivalencies? >>>> >>>> >>> >>> Really? You think I need to? >>> >> >> Yes, I think you need to. If this is only going to save a half a second >> of CPU time per day, I'm not going to build an ORM to get it. The question >> isn't how much faster the identity check is (and I don't think it's that >> much faster) -- the question is how much of your overall application CPU >> time is spent doing this kind of thing? >> >> Anthony >> > -- --- You received this message because you are subscribed to the Google Groups "web2py-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to web2py+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
