On Wed, Oct 14, 2009 at 11:34 AM, Wouter <wiegm
...@gmail.com> wrote:
> The summaries are never recalculated. Once a summary has been created,
> it is updated in real time using $inc. I need real time summaries.
> Let's say I'm offering real time analytics using Mongo (http://
> blog.mongodb.org/post/171353301/using-mongodb-for-real-time-
> analytics), but I also save info about each visit, and I allow
> customized reports.
> So with every visit:
> 1) Upsert data for this visitor in the visits collection.
> 2) Update all reports to which this visitor belongs (using $inc)
> Initially, there is one report (summary document): the one that
> includes all visitors to the site.
> Now, users can create their own customized reports. EG: generate a
> report for all US visitors that spend at least 5 minutes on my site.
> 1) Retrieve all visit data find({ site_id : 123, country : 'US',
> total_time : { $gt : '300' }})
> 2) Calculate summary (number of visits, time_spent, other statistics)
> 3) Store results in summary document (db.reports.insert ({ ...}))
> 4) Update summary document when data is updated/added.
> (db.reports.update( { total : $inc .... })
> Now, if a US visitor is active on the site between step 1 and step 3,
> the report could end up being incorrect...
> How to prevent that :-)
> On 14 okt, 16:51, dwight_10gen <dwi...@10gen.com> wrote:
> > how often do you want to (re)calculate the summarizes? near realtime
> > or infrequent (daily)?
> > On Oct 14, 10:34 am, Wouter <wiegm...@gmail.com> wrote:
> > > I want to be able to create 'summary documents' (the Mongo equivalent
> > > of summary tables :-)).
> > > Once the summary document is created, it will be updated using $inc /
> > > $set, meaning the summary will be always up to date (that's what I
> > > need :-)).
> > > The process to create a summary looks like this:
> > > 1) Retrieve relevant data
> > > 2) Calculate summary
> > > 3) Store results in summary document
> > > 4) Update summary document when data is updated/added.
> > > However, if data is added/updated between step 1 and step 3, the
> > > summary will be incorrect. Any suggestions how to deal with this?!
