Hi Richard, On Sat, Jan 15, 2011 at 12:05 PM, Richard Arrano <[email protected]>wrote:
> Thanks for the response! I was thinking it over and I have a question > - so if a timestamp with its monotonically increasing index causes a > performance hit at a high write rate, would updating the high bid do > so as well ? The high bid itself will be monotonically increasing - it > will never go down, but perhaps I misunderstood something about how > indices work. > See the reply I just sent - while it's true that something like the increasing bid would cause the same issue, it's not going to be a problem at the sort of write rate you're likely to see here. > > And I guess a broader question that I have is(and I assume the answer > is yes) - does the size of what we're writing affect the performance? > As in, writing a simple update to an integer property as opposed to > creating new complex objects and writing them. > To a small degree, yes, the size of the object will affect the overhead, but it's not the largest factor - other things like the number of index rows you have per entity will have a much bigger impact. Note that the size that's significant is the size of your whole entity, not the amount of data you're changing. -Nick Johnson > Thanks, > Richard > > On Jan 14, 10:05 am, "Ikai Lan (Google)" > <[email protected]<ikai.l%[email protected]> > > > wrote: > > You can certainly write to Memcache, but I don't think your application > can > > tolerate any kind of volatility. Persistence is the price you have to > pay. > > Fortunately, I think this can be done pretty cheaply. Just be aware of > > monotonically increasing indexes like timestamps: if you have an > application > > with a high write rate that has a timestamp, this will cause the > persistence > > unit storing the indexes to be unable to be autosplit easily across > multiple > > hardware instances and you will take a performance hit. The solution here > > is, again, to shard the timestamp by prefixing a value to distribute the > > writes. > > > > -- > > Ikai Lan > > Developer Programs Engineer, Google App Engine > > Blogger:http://googleappengine.blogspot.com > > Reddit:http://www.reddit.com/r/appengine > > Twitter:http://twitter.com/app_engine > > > > On Fri, Jan 14, 2011 at 6:06 AM, Richard Arrano <[email protected] > >wrote: > > > > > I'm looking to make a silent-auction type of application where you > > > have 20-30 users bidding on an item at a time, with potentially > > > hundreds or thousands of auctions happening simultaneously. As soon as > > > a high bid is made, it updates this information and sends it via the > > > Channel API to the other users in the auction. I see two potential > > > difficulties: > > > > > 1. The limit on updating an entity group about once per second - I > > > believe this can be solved with sharding bids amongst users in the > > > auction and querying all shards to find the maximum bid at any given > > > time, correct? > > > > > 2. The nature of the auction lends itself to a heavy amount of > > > writing to the datastore - this itself eats up CPU and I’m trying to > > > figure out if it can be avoided. Is this just inevitable in this type > > > of application? Does it matter that I would only be only updating a > > > single IntegerProperty() in any given write? Is there some clever > > > solution that we can apply that avoids the hammering of the datastore? > > > > > Any tips or suggestions would be appreciated. > > > > > Thank you, > > > Richard > > > > > -- > > > You received this message because you are subscribed to the Google > Groups > > > "Google App Engine" group. > > > To post to this group, send email to [email protected] > . > > > To unsubscribe from this group, send email to > > > [email protected]<google-appengine%[email protected]> > <google-appengine%[email protected]<google-appengine%[email protected]> > > > > > . > > > For more options, visit this group at > > >http://groups.google.com/group/google-appengine?hl=en. > > > > > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<google-appengine%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/google-appengine?hl=en. > > -- Nick Johnson, Developer Programs Engineer, App Engine Google Ireland Ltd. :: Registered in Dublin, Ireland, Registration Number: 368047 -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to [email protected]. 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.
