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Another gotcha we found is that you can't do any type of real-time aggregation in a production environment. There is a group() function, and there is Map Reduc
by Sym3tri 15y ago
Another gotcha we found is that you can't do any type of real-time aggregation in a production environment.
There is a group() function, and there is Map Reduce, but since they both run via the JavaScript engine and the nature of JavaScript is single-threaded that means that you can never execute more than one of the aggregation queries at a time. So if an aggregation query is taking a long time to run, all other queries will block and potentially timeout.
Supposedly we'll have better options in 2.0.
- latch 15y agoIn addition to supporting multi-threaded map-reduce, it'd be nice if they 1- Eliminate any memory limits on inline map reduce, or bring back output to temporary collections. If they bring back output to temporary tables, allow them to be run on slaves and not participate in replication 2- Polished and released a production-ready version of their MongoDB Hadoop Adapter: https://github.com/mongodb/mongo-hadoop https://github.com/mongodb/mongo-hadoop