This is also pertinent: http://www.mongodb.org/display/DOCS/How+does+concurrency+work http://www.mongodb.org/display/DOCS/How+does+concurrency+wor... Note tha

This is also pertinent: http://www.mongodb.org/display/DOCS/How+does+concurrency+work http://www.mongodb.org/display/DOCS/How+does+concurrency+wor... Note that whilst a write blocks all other writes, the time you need to wait is the time it takes for the in-memory data structure to be modified; you don't have to wait for the write to hit disk. (Writes are only persisted to disk every so often.)