I really don't see how you couldn't replace MongoDB in that post with any other database and still be presented with the same issues:
- adding indexes slows writes down and increases memory requirements
- running queries with poor / no indexes will cause you to have I/O constraints and an unhappy CPU
- it seems like your data set was better suited for a graph db like neo4j than a document db or RDBMS.
As for the data corruption, I didnt see you mention if you were checking for a response on saves or not.
I think the problems you experienced were due much more to the fact that you apparently had more data than the machine could handle, not necessarily the database engine used.
See the subsequent writeup on SQLite and how it handled the same dataset magnificently. About the checking of responses, if you read the article you will see that previously stored data just went away, it wasn't failure to store outright.
Given that you didn't know better than to not use 1.3.* initially I find it hard to take your continued propagation of your posts on MongoDB seriously.
http://www.korokithakis.net/posts/using-mongodb-for-great-sc...