Map/Reduce error 10293 using a $within $box query

[Andrew Bloom]

I'm having a bit of a problem folks. I've got a rather large dataset (~4.5 million records) with a very simple "schema" (1). I'm trying to run a map/reduce query over a subset of this data (2) and generate some counts but the query seems to cause Mongo to blow up (3). I've spent a few weeks reading and experimenting and have failed. I know the geo spacial indexing works as I've included a $within $box count before running the map/reduce and see 119236 results.

Can anyone make sense of this? Please tell me what I'm doing wrong. I know as a work around I could run the query, build a new collection and then map/reduce over the new collection but I'd really love to keep this as simple as possible as I plan on running this from Ruby with MongoMapper. I'm only experimenting with the Mongo console and JS scripts while trying to debug this issue.

Thanks

Andrew

[1]: https://gist.github.com/1257749#file_incident.rb

[2]: https://gist.github.com/1257749#file_script.js

[3]: https://gist.github.com/1257749#file_mongo.log

[Greg Studer]

Think this may be an issue with large intermediate result sets and non-
yielding cursors - but to double check, is it possible to run a
modified form of the query in a smaller area which only returns a few
results (< 600 or so?)

[Andrew Bloom]

Greg,

Thanks. I think you're onto something. I kept experimenting with this yesterday and tried exactly that, it worked perfectly.

Do you have any ideas how to keep Mongo from crashing with these large sets?

Thanks

Andrew

[Greg Studer]

For now, unfortunately, I think the workaround is to build the new
collection, as you hoped not to do, or tile the larger region into a
set of smaller regions to M/R sequentially.
Also opened SERVER-4002 to track.

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