A few of the major issues I've seen around are the global write lock which is starting to get taken care of. The reliance on the OS to cache instead of intelligently caching based off data. Poor fail over support. Sharding not being a "turn key" solution like it was supposedly advertised as, misconfiguring it can lead to poor performance. Bringing extra nodes online can take a long time for data to migrate over to the new nodes.
Scaling has a number of components to it - it's not just about the absolute number of requests. There are always trade-offs (read up about the CAP theorem). My experience with Mongo has been that it has very inconsistent performance. Such inconsistency makes capacity planning very difficult. Also - stuff like failover, sharding etc. are not elegant.
Klinky|13 years ago
karterk|13 years ago