3 ms·
Your folks were wrong. They lock on the collection and only on some types of queries.
by moox 13y ago
Your folks were wrong. They lock on the collection and only on some types of queries.
- scottbessler 13y agoNo, they lock the entire database for every write. "MongoDB uses a readers-writer [1] lock that allows concurrent reads access to a database but gives exclusive access to a single write operation." "Beginning with version 2.2, MongoDB implements locks on a per-database basis for most read and write operations. Some global operations, typically short lived operations involving multiple databases, still require a global “instance” wide lock. Before 2.2, there is only one “global” lock per mongod instance." source: http://docs.mongodb.org/manual/faq/concurrency/ http://docs.mongodb.org/manual/faq/concurrency/
- MichaelGG 13y agoYes that's the part that just kills me. It was a system-wide lock, and now it's just per-DB. I just don't see how anyone can take that seriously. Also, why bother with a buffer pool manager when you've got mmap, right?