PostreSQL can't horizontally scale easily or properly handle JSON right now compared to MongoDB. It also has a fixed schema which makes database migrations a necessary evil again. Sorry but the idea that PostgreSQL is a feature by feature replacement is pretty laughable.
Easily being the appropriate word here. In that article you wrote they had to manually setup sharding. With something like CouchDB I can press a button to add a new node in the cluster. Again. Easily is what I am talking about.
And again V8 is nice and all but it is rather bolted on as opposed to something that is was built from scratch to support JSON. This shows in terms of feature support and most importantly ease of use. I can't just annotate HashMaps, Lists etc in my Java classes and have them serialized to PostgreSQL in JSON format.
I am just saying that PostgreSQL is a great and all but it is not a proper JSON document store style database anymore than hacking SQL on top of MonogDB would make it a RDBMS.
I noticed that Mattdebord's post qualified it by saying feature-for-feature replacement of Mongodb for us. He didn't claim it was for everyone. Why all the hate?
Maybe not easily but it can far more flexibly than MongoDB. Take a look at Postgres-XC which offers a two-tiered clustering solution for Postgres inspired by Teradata. A bit complex, but you don't give up your formal proof of data integrity in order to get it.
PostreSQL can't horizontally scale easily or properly handle JSON right now compared to MongoDB. It also has a fixed schema which makes database migrations a necessary evil again. Sorry but the idea that PostgreSQL is a feature by feature replacement is pretty laughable.