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Comment by mglukhovsky | Hacker News Reader

Here's what this query looks like in RethinkDB (also based on JSON documents):

  r.table('orders')
   .pluck('cust_id','ord_date','price')
   .groupBy('cust_id','ord_date', r.sum('price')).
   .filter(r.row('reduction').gt(250))

We use the hard-coded attribute 'reduction' because groupBy automatically gets compiled to our distributed map-reduce infrastructure. There is currently no as command (though it could easily be simulated with map). I'll add a GitHub issue for this shortly, since we should add sugar for it.

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The beauty of JSON is you could incredibly easily write such jquery like chained expression to generate the mongo query. JSON is a good ascii representation of structured data thats compact, quite readable and reasonably human editable.

Its not an abuse of JSON to use it as a way of representing queries, but its probably a shame that Mongo haven't provided a better way of generating queries.

Totally agree with you.

What are the main differences between MongoDB and RethinkDB? Things that you hear people care about? I don't use Mongo but I've seen projects that use it. I ask because I want to store & retrieve some analytics.

After seeing the screencast of RethinkDB it seems to me that it's just like Mongo but a much better API and easier handling of sharding and replication. The only con I see of using RethinkDB is that it's very new (so is Mongo...) and probably is little too early for production. Basically I hope not to find worse surprises down the road than I hear of Mongo :P

We're going to publish some comparisons in a few days, but basically you nailed it (both pros and con). We're trying to build a stellar data-oriented development environment/query language, and a stellar scalability infrastructure. All the main pieces are there, and Rethink is a lot of fun to use. The rough edges will be polished out in over the next few months.

Most ORMs use dot notation, even for mongo (e.g. mongo engine) to build queries. I think the mongo queries are more true to what it should be since dot notation in most languages implies a function/method is being called and order matters in those cases. Here it's just acting like a query builder that runs with .run().

Under the same effect I'm not a fan of mongo style query({}).limit(count).skip(num) format and usually I move the limit and skip into the initial query.

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