replication: All content tagged as replication in NoSQL databases and polyglot persistence
I have two mongod instances without replication each having same collection name but different data.Now initialized replication between them.Secondary machine copies all data from primary machine and looses it’s original data.Can I recover original data present in secondary machine ?
Leaving aside the typos in the question (and any resentments they might generate), would you consider this the expected behavior? To me this sounds like a conflict in the setup and the database should error.
Original title and link: Oops Replication - MongoDB Secondary Node Data Loss ( ©myNoSQL)
Mat Keep and Bernd Ocklin discuss what’s new in the second milesone release of MySQL Cluster 7.2: performance improvements, new NoSQL access (memcached protocol), cross data center scalability. Download the mp3.
Original title and link: Podcast: MySQL Cluster News: Performance Improvements,New NoSQL Access ( ©myNoSQL)
I’m seeing many questions asked
 about MongoDB replication and sharding, so I thought it might be an idea to try to gather the most interesting ones and submit them to the MongoDB/10gen people to get some answers. So, after reading the documentation on MongoDB replica sets
 and MongoDB sharding
, what questions would you want answered?
Please post a comment with your questions and I’ll be adding them to the list. After accumulating a couple of good questions I’ll forward them to MongoDB/10gen people for answers.
To start with, here are a couple from me:
- What may be causing replica sets to lag behind the master or become “disconnected” (except network partitions)?
- How would one determine the best size of sharding “chunks”?
- Is it possible and what would lead to an unbalanced cluster?
What are yours? Feel free to forward it to any friends using MongoDB that are looking into using replica sets and sharding.
Note: I’m not planning to create yet another forum or Q&A site, so I’ll make sure that once we get some answers these will be published in a place where everyone interested will find them easily.
Note: If you are interested in getting answers about other NoSQL database, please let me know and I’ll create the initial list.
- Not only on the ☞ MongoDB group, but also on Quora.com, StackOverflow.com and blogs (↩)
- MongoDB replica sets resources (↩):
- MongoDB sharding resources (↩):