Planet NoSQL

  In the article on MongoDB and Couchbase   database objects , we saw the mapping from databases to buckets, collections to collections, documents to documents and  field to fields. The data itself is stored within these fields. The {"field": "value"} is commonly called key-value pairs. Every key has a value and the value is the data. This value self describes the data under  BSON or JSON definition in MongoDB and Couchbase. MongoDB uses BSON, Couchbase uses JSON -- both are document oriented and JSON based. Couchbase uses JSON exactly, MongoDB uses extended JSON called BSON,  binary JSON . As part of data remodeling, while moving from the relational model to the JSON model, you’ll have to consider the data type mapping. In Oracle, you’ll have to create and declare the types of each column explicitly before you load the data or write queries. In Couchbase, you simply conform to JSON syntax and the data type interpretation is automatic and implicit. Here’s the ov...

    MongoDB developers and DBAs work with physical clusters, machines, instances, storage systems, disks, etc. All MongoDB users, developers, and their applications work with logical entities: databases, collections, documents, fields, shards, users, data types.  There are a lot of similarities with Couchbase since both are document (JSON) oriented databases.  Let’s compare and contrast the two with respect to database objects.  Here’s the first part of this series comparing the architecture.   MongoDB Organization A full list of MongoDB schema objects is listed here and here . A database instance can have many databases; A database can have many collections; Each collection can have many indexes.  Each collection can be sharded based into multiple chunks on multiple nodes of a cluster using hash-sharding strategy or index sharding strategy.  The MongoDB indexes are local to their data.  Therefore, the indexes use the same strategy as ...