In this blog post, I’ll discuss my top five go-to tips for MongoDB troubleshooting.
Every DBA has a war chest of their go-to solutions for any support issues they run into for a specific technology. MongoDB is no different. Even if you have picked it because it’s a good fit and it runs well for […]
Over several posts, I’ve explained the differences between TokuMX replication and MongoDB replication, and why they are completely incompatible. In this (belated) post, I explain one last difference: the oplog format for operations. Specifically, TokuMX and MongoDB log updates and deletes differently.
Suppose we have a collection foo, with the following element:
Shell
rs0:PRIMARY> db.foo.find()
{ “_id” : […]
In a post last week, I described the difference in concurrency behavior between MongoDB’s oplog and TokuMX’s oplog. In short, here are the key differences:
MongoDB protects access to the oplog with a database level reader/writer lock, whereas TokuMX does not.
TokuMX can write data to the oplog concurrently, whereas MongoDB cannot.
As a result, because a […]
In my last post, I describe the differences between a TokuMX oplog entry and a MongoDB oplog entry. One reason why the entries are so different is that TokuMX supports multi-statement and multi-document transactions. In this post, I want to elaborate on why multi-statement transactions cause changes to the oplog, and explain how we […]
Read moreAs I mentioned in my last post, TokuMX replication is completely incompatible with MongoDB replication. Replica sets (and sharded clusters, but that is for another blog) must be either entirely TokuMX or entirely MongoDB. This is by design. While elections and failover are basically the same, we have completely changed the oplog protocol.
In the […]
