Postgres Blog: Learning from NoSQL
Bruce Momjian definitely gets it:
I think the primary lesson the Postgres community can learn from NoSQL is that not everyone needs all our features, and if it can be easily accomplished, we should allow users to trade features for some of the NoSQL desired behaviors.
He goes on and provides a couple of possible such tradeoffs: speed vs durability (nb see for example MongoDB durability tradeoff), arrays vs joins, non-structured data storage, bypassing query parser and optimizer overhead, etc.
via: http://momjian.us/main/blogs/pgblog/2010.html#April_10_2010_2
