Roles and Responsibilities As with any database, applications deployed on MongoDB require careful planning and the coordination of a number of roles in an organization’s technical teams to ensure successful maintenance and operation. Organizations tend to find many of the…
MongoDB does not support joins. In MongoDB some data is denormalized, or stored with related data in documents to remove the need for joins. However, in some cases it makes sense to store related information in separate documents, typically in different…
On Selecting a Shard Key for MongoDB – Bad-Ass Unicorn One of the killer features of MongoDB is the built-in sharding capabilities. This feature lets you spread out both your data, and your database workload, over multiple commodity-scale machines. While…
Shard Keys¶ The shard key determines the distribution of the collection’s documents among the cluster’s shards. The shard key is either an indexed field or an indexed compound field that exists in every document in the collection. MongoDB partitions data…
This post describe on how to use write concerns in MongoDB and how it impacts durability, performance and resiliency. Write Concerns: This describes the level of concern or guarantee the server will provide in its response to a write operation….
The voting is done by a majority of voting members. Imagine a Replica Set with three (voting) members. Let’s say that Node A is primary, and nodes B+C are secondaries. Node A goes down, so nodes B+C go to election….
This blog was originally posted by David Ostrovsky here on August 11th 2014 TL;DR: Replicate documents from Couchbase to ElasticSearch through XDCR and display real-time analytics in Kibana. For the less impatient readers, I’d like to tell you about an interesting use-case for…
This blog was originally posted by David Ostrovsky here on August 11th 2014 TL;DR: The most compact printable ASCII encoding of a binary value is Ascii85 (aka. Base85). Encoding a 16-byte UUID as Base85 takes only 20 bytes, as opposed to 36 for…
Memory-Mapped Persistence But let me start at the beginning, MongoDB’s persistence cycle, and then get to what’s being done to improve its reliability and your data’s durability. At the very heart, MongoDB uses memory-mapped files to store data. A memory-mapped…
Write-Ahead Logging (WAL) Write-Ahead Logging (WAL) is a standard method for ensuring data integrity. A detailed description can be found in most (if not all) books about transaction processing. Briefly, WAL‘s central concept is that changes to data files (where…