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Comment by netcraft | Hacker News Reader

so are we saying that

    r.table('users').filter(function(user){return user('signup_date').gt(signupFilter);}).run(...

is running this filter in the database, not in node?

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It does run on the database server-- see the documentation for more information: http://rethinkdb.com/api/javascript/filter/

They key line(s) is/are:

Predicates to filter are evaluated on the server, and must use ReQL expressions. You cannot use standard JavaScript comparison operators such as ==, </> and ||/&&.

It's essentially equivalent to:

r.table('users').filter(r.row("signup_date").gt(signupFilter)).run(conn, callback);

ah, that makes a bit more sense. Still impressive though. Thanks for the information.

Am I correct in assuming that the implementation is similar to that of LINQ and ORMs like NHibernate or Entity Framework? Example: https://msdn.microsoft.com/en-us/data/jj573936.aspx

Yes, that's right. If you want to know how it's implemented, check out this post -- http://rethinkdb.com/blog/lambda-functions/, it goes into quite a bit of depth into how the drivers work.

A small note -- you can use arbitrary javascript expressions with the `r.js` command (rethinkdb.com/api/javascript/js/).

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