Mongo's probably still got the edge as a JSON store overall, but definitely check out the new JSON object dereferencing functionality coming in 9.3. There's a Russian indexing posse consisting of Oleg, Teodor, and Sasha who have been looking at doing proper indexes for JSON but haven't managed to secure funding. (Disclosure: I think they should get funded.)

These are the same guys who built hstore, full text search, GIN and GIST indexes and I think are working on a generic regular expression index type right now.

> "We use MySQL, MongoDB, PostgreSQL, and Impala."

Thanks for the clarification, but this makes it even more obvious your engineering team is introducing needless complexity into your organization.

Postgres can store unstructured data just fine, so you have a 'solution' that uses 3 OLTP stores instead of one.

PostgreSQL is awful for storing unstructured data. It is the most cumbersome, clunky syntax I've seen for a while and it lacks ORM support meaning you are forced to manually write it.

Making developers productive is an important aspect for choosing a database.

Choosing a data store based upon syntax and slightly limited ORM support isn't exactly a great idea. Both of these things can be improved rapidly with a little code.

More important questions are how is the data stored, how is it accessible, how can you scale the system, what operational constraints are there, how fast is it, what types of data modeling can be done, what consistency/transaction guarantees does it provide, etc. These are the things that will make developers productive because they will not be putting out fires all the time.

well said!

Why do you use MySQL over Postgres and vice versa?

(Clouderan here)

How are you liking Impala? We just dropped 0.5 release yesterday which includes the JDBC driver :D!

Edit: Awesome job on the Ruby client, it's great!

It's been great -- setup was a bit of work (we're on Ubuntu, so had to build from source), but once up and running it's allowed us to do lots of ad-hoc analysis that would have been too hard otherwise.

I've been meaning to write a MoSQL equivalent for our Impala data, but at the moment we're doing a more traditional ETL.

gdb - If you have Impala, Hadoop, and Hive right now. Why use MongoDB instead of HBase and make it all work in a happy harmony?

Awesome! Great to hear it's working out for you guys, looking forward to MoSQL for Impala :-)

We've been pretty happy so far. There have been a few rough edges getting it up and keeping it running, but we've been very impressed with the performance so far.

I've passed your comment on to Colin, who wrote the Ruby client -- I'm sure he'll appreciate it!

I got myself a little Impala Herd server setup, pointed it at my Impala cluster and it's working great ;).

heh, I didn't think anyone would actually use that - I originally wrote it meaning to use it as a tutorial for the blog post, then scrapped that idea.

Thanks for the kind words!