Plain text files in a filesystem Very simple to create and edit Easy for users to manipulate with simple tools (i.e. text editors, grep etc) Efficient storage of binary documents XML or JSON files on disk As above, but with a bit more ability to validate the structure. Spreadsheet / CSV file Very easy model … Read more
Eventual consistency: I watch the weather report and learn that it’s going to rain tomorrow. I tell you that it’s going to rain tomorrow. Your neighbor tells his wife that it’s going to be sunny tomorrow. You tell your neighbor that it is going to rain tomorrow. Eventually, all of the servers (you, me, your … Read more
Hadoop is basically 3 things, a FS (Hadoop Distributed File System), a computation framework (MapReduce) and a management bridge (Yet Another Resource Negotiator). HDFS allows you store huge amounts of data in a distributed (provides faster read/write access) and redundant (provides better availability) manner. And MapReduce allows you to process this huge data in a … Read more
Just promise yourself that you will never try to map a relational data model to a NoSQL database like MongoDB or CouchDB… This is the most common mistake developers make when evaluating emerging tech. That approach is analogous to taking a car and trying to use it to pull your cart down the road like … Read more
Given your current table structure this is not currently possible in DynamoDB. The huge challenge is to understand that the Hash key of the table (partition) should be treated as creating separate tables. In some ways this is really powerful (think of partition keys as creating a new table for each user or customer, etc…). … Read more
MongoDB is strongly consistent by default – if you do a write and then do a read, assuming the write was successful you will always be able to read the result of the write you just read. This is because MongoDB is a single-master system and all reads go to the primary by default. If … Read more
A key-value store provides the simplest possible data model and is exactly what the name suggests: it’s a storage system that stores values indexed by a key. You’re limited to query by key and the values are opaque, the store doesn’t know anything about them. This allows very fast read and write operations (a simple … Read more
See following links CouchDB Vs MongoDB MongoDB or CouchDB – fit for production? DB-Engines – Comparison CouchDB vs. MongoDB Update: I found great comparison of NoSQL databases. MongoDB (3.2) Written in: C++ Main point: JSON document store License: AGPL (Drivers: Apache) Protocol: Custom, binary (BSON) Master/slave replication (auto failover with replica sets) Sharding built-in Queries … Read more
Not all data is relational. For those situations, NoSQL can be helpful. With that said, NoSQL stands for “Not Only SQL”. It’s not intended to knock SQL or supplant it. SQL has several very big advantages: Strong mathematical basis. Declarative syntax. A well-known language in Structured Query Language (SQL). Those haven’t gone away. It’s a … Read more