Before proposing a solution, what is your expected active user base. 1000's or 1,000,000s or something in between. Steve
On Apr 6, 3:50 pm, Matt Hall <matt.h...@gmail.com> wrote: > Thanks for the response, could you point me to somewhere where I can > read about batched queries by key in JDO? Or do I need to go to the > low level API for that? > > I think the conclusion I'm coming to here is 1) I shouldn't have made > the detail for each order as a separate object, (although this has > huge problems for querying later as in how many people have bought > item x), and 2) JDO managed relationships get slow with small numbers > of child objects, are hard to optimize, and probably not worth the > trouble overall. Is that pretty much what I should be concluding? > > Thanks again, I'm really trying to understand how to translate what's > a basic structure in RDMS land into something that will work in app > engine beyond toy implementations. > > On Apr 6, 12:54 pm, "Ikai L (Google)" <ika...@google.com> wrote: > > > For speed, you'll get the most gains if you denormalize when possible - yes, > > the relational purists are going to riot, but you don't have many of the > > benefits of normalization anyway such as foreign key constraints or native > > joins. > > > If that isn't an option - and I really do recommend looking into it where it > > makes sense - if you're able to retrieve keys, we may also be able to make > > use of batch queries by key. > > > On Mon, Apr 5, 2010 at 2:59 PM, Matt Hall <matt.h...@gmail.com> wrote: > > > Hi Everyone, > > > > I've been trying for the past while to get our relatively simple JDO > > > based site to run at a reasonable speed, but I'm failing and I'd love > > > any suggestions. I'll describe it as succinctly as possible to > > > hopefully keep your interest :) > > > > * The basic structure is a User -> Order -> Line items type > > > structure. > > > * The main query performed is "Orders for a user." > > > * A user usually has around 10 orders, each order has under 100 line > > > items. > > > * The Order -> Items relationship is done as a One-to-many owned > > > relationship. > > > > My problem is that the basic request the site handles: "Get all orders > > > for a user and do something based on the line items" is very slow. In > > > real response time, my average is now 1.5 seconds, and some of the > > > users are seeing 20 second response times. Clearly not ok. > > > > What appears to be slow, after profiling with the new app stats tool > > > is that each line item is getting loaded as it's used (lazy loading), > > > which works great in some cases but terrible in this case since each > > > item takes 20-30ms to load. > > > > I have tried: > > > > * Moving items into the default fetch group for orders, seems to have > > > no effect (may not even be possible due to limitations of joins) > > > * Level 2 caching with memcache - not much effect either since only > > > the individual line items are cached, not the whole List, so we still > > > pay a price in round trip to the cache on each line item. > > > * A sort of wacky cache that I wrote on top of the JDO managed > > > relationship to cache the whole collection. This went poorly and > > > resulted in odd data inconsistencies, probably because I did something > > > wrong but the whole thing felt wrong. > > > > So my question is - what am I doing wrong? What's the best/standard > > > way to represent a Master -> Detail type relationship, where the total > > > items for a user will be relatively small but requests need to work > > > with a fair number of them. > > > > Thanks for any suggestions, I'd be happy to answer any questions if > > > what I've written isn't clear. > > > > Matt > > > > -- > > > You received this message because you are subscribed to the Google Groups > > > "Google App Engine for Java" group. > > > To post to this group, send email to > > > google-appengine-j...@googlegroups.com. > > > To unsubscribe from this group, send email to > > > google-appengine-java+unsubscr...@googlegroups.com<google-appengine-java%2B > > > unsubscr...@googlegroups.com> > > > . > > > For more options, visit this group at > > >http://groups.google.com/group/google-appengine-java?hl=en. > > > -- > > Ikai Lan > > Developer Programs Engineer, Google App > > Enginehttp://googleappengine.blogspot.com|http://twitter.com/app_engine -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
