[vog]

> JSON type and functional indexes

Those "Indexes on Expressions" are really a great feature that can also be combined with XML (not just JSON) and any other types. I recommend everyone to have a look at those:

http://www.postgresql.org/docs/9.2/static/indexes-expression...

[arethuza]

Is there any way in those expressions to parse JSON and perform arbitrary calculations - i.e. like CouchDB views?

[zurn]

Sure, you can write server side procedures in f.ex. javascript that do arbitrary things with the json.

[vog]

To be fair, one should note that "only" the languages C, Python, Perl and Tcl [1] are officially supported by PostgreSQL. Also, there are 3rd-party bindings for other languages such as Java, PHP, R, Ruby, Scheme, sh:

http://www.postgresql.org/docs/9.2/interactive/external-pl.h...

However, the PostgreSQL documentation doesn't mention JavaScript support anywhere. Are you sure there exists mature PL/JavaScript binding for PostgreSQL? If so, their docs should be updated.

[1] There's also "pgSQL", but that's a special-purpose language you won't find outside the database world. I don't recommend learning it unless you have strange requirements that make PL/pgSQL a perfect fit. For normale usage, use PL/Python or PL/Perl. In simple cases, use SQL directly.

[zurn]

Yes, #1 hit when you Google for postgresql JavaScript: https://code.google.com/p/plv8js/

I can't vouch for any particular maturity level but seems to have active users and it's been around a few years already.