Hey Carles, Glad it seems helpful. I am hoping to get time today to push out some revisions and sample code.
Robert On Thu, Oct 14, 2010 at 05:50, Carles Gonzalez <[email protected]> wrote: > Robert, I took a brief inspection at your code and seems very cool. Exactly > what i was lloking for for my report generation and such. > I'm looking forward for more examples, but it seems a very valuable addition > for our toolbox. > Thanks a lot! > > On Wed, Oct 13, 2010 at 9:20 PM, Carles Gonzalez <[email protected]> wrote: >> >> Neat! I'm going to see this code, hopefully I'll understand something :) >> On Wednesday, October 13, 2010, Robert Kluin <[email protected]> >> wrote: >> > Hey Dmitry, >> > In case it might help, I pushed some code to bitbucket. At the >> > moment I would (personally) say the code is not too pretty, but it >> > works well. :) >> > http://bitbucket.org/thebobert/slagg >> > >> > Sorry it does not really have good documentation at the moment, but >> > I think the basic example I threw together will give you a good idea >> > of how to use it. I need to do another cleanup pass over the API to >> > make a few more refinements. >> > >> > I pulled this code out of one of my apps, and tried to quickly >> > refactor it to be a bit more generic. We are currently using >> > basically the same code in three apps to do some really complex >> > calculations. As soon as I get time I will get an example up showing >> > how to use it for neat stuff, like overall, yearly, monthly, and daily >> > aggregates across multiple values (like total dollars and quantity). >> > The cool thing is that you can do all of those aggregations across >> > various groupings, like customer, company, contact, and sales-person, >> > at once. I'll get that code pushed out in the next few days. >> > >> > Would love to get some feedback on it. >> > >> > >> > Robert >> > >> > >> > >> > >> > >> > On Tue, Oct 12, 2010 at 17:26, Dmitry <[email protected]> wrote: >> >> Ben, thanks for your code! I'm trying to understand all this stuff >> >> too... >> >> Robert, any success with your "library"? May be you've already done >> >> all stuff we are trying to implement... >> >> >> >> p.s. where is Brett S.:) would like to hear his comments on this >> >> >> >> On Sep 21, 1:49 pm, Ben <[email protected]> wrote: >> >>> Thanks for your insights. I would love feedback on this implementation >> >>> (Brett S. suggested we send in our code for >> >>> this)http://pastebin.com/3pUhFdk8 >> >>> >> >>> This implementation is for just one materialized view row at a time >> >>> (e.g. a simple counter, no presence markers). Hopefully putting an ETA >> >>> on the transactional task will relieve the write pressure, since >> >>> usually it should be an old update with an out-of-date sequence number >> >>> and be discarded (the update having already been completed in batch by >> >>> the fork-join-queue). >> >>> >> >>> I'd love to generalize this to do more than one materialized view row >> >>> but thought I'd get feedback first. >> >>> >> >>> Thanks, >> >>> Ben >> >>> >> >>> On Sep 17, 7:30 am, Robert Kluin <[email protected]> wrote: >> >>> >> >>> > Responses inline. >> >>> >> >>> > On Thu, Sep 16, 2010 at 17:32, Ben <[email protected]> >> >>> > wrote: >> >>> > > I have a question about Brett Slatkin's talk at I/O 2010 on data >> >>> > > pipelines. The question is about slide #67 of his pdf, >> >>> > > corresponding >> >>> > > to minute 51:30 of his talk >> >>> > >> >>> > > >http://code.google.com/events/io/2010/sessions/high-throughput-data-p... >> >>> >> >>> > > I am wondering what is supposed to happen in the transactional >> >>> > > task >> >>> > > (bullet point 2c). Would these updates to the materialized view >> >>> > > cause >> >>> > > you to write too frequently to the entity group containing the >> >>> > > materialized view? >> >>> >> >>> > I think there are really two different approaches you can use to >> >>> > insert your work models. >> >>> > 1) The work models get added to the original entity's group. So, >> >>> > inside of the original transaction you do not write to the entity >> >>> > group containing the materialized view -- so no contention on it. >> >>> > Commit the transaction and proceed to step 3. >> >>> > 2) You kick off a transactional task to insert the work model, or >> >>> > fan-out more tasks to create work models :). Then you proceed to >> >>> > step 3. >> >>> >> >>> > You can use method 1 if you have only a few aggregates. If you have >> >>> > more aggregates use the second method. I have a "library" I am >> >>> > almost >> >>> > ready to open source that makes method 2 really easy, so you can >> >>> > have >> >>> > lots of aggregates. I'll post to this group when I release it. >> >>> >> >>> > > And a related question, what happens if there is a failure just >> >>> > > after >> >>> > > the transaction in bullet #2, but right before the named task gets >> >>> > > inserted in bullet #3. In my current implementation I just left >> >>> > > out >> >>> > > the transactional task (bullet point 2c) but I think that causes >> >>> > > me to >> >>> > > lose the eventual consistency. >> >>> >> >>> > Failure between steps 2 and 3 just means _that_ particular update >> >>> > will >> >>> > not try to kick-off, ie insert, the fan-in (aggregation) task. But >> >>> > it >> >>> > might have already been inserted by the previous update, or the next >> >>> > update. However, if nothing else kicks of the fan-in task you will >> >>> > need some periodic "cleanup" method to catch the update and kick of >> >>> > the fan-in task. Depending on exactly how you implemented step 2 >> >>> > you >> >>> > may not need a transactional task. >> >>> >> >>> > Robert >> >>> >> >>> > > Thanks! >> >> > > -- > 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. > -- 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.
