MongoDB Operations — Trivia & Interesting Facts¶
Surprising, historical, and little-known facts about MongoDB operations.
MongoDB's name comes from "humongous"¶
MongoDB was created by Dwight Merriman, Eliot Horowitz, and Kevin Ryan at 10gen (later renamed MongoDB Inc.) in 2007. The name is derived from "humongous," reflecting the database's ambition to handle massive amounts of data. The company changed its name from 10gen to MongoDB Inc. in 2013 because the product had become more famous than the company.
MongoDB did not support multi-document transactions until version 4.0 in 2018¶
For its first 9 years, MongoDB could only guarantee atomicity for operations on a single document. Multi-document transactions, considered a basic requirement for most applications, were not available until version 4.0 (2018). This limitation was one of the most criticized aspects of MongoDB and led to countless data consistency bugs in early adopters' applications.
The "MongoDB is web scale" meme shaped an entire technology debate¶
A satirical YouTube video titled "MongoDB is Web Scale" (2010) mocked the NoSQL hype of the early 2010s, with characters dismissing relational databases because MongoDB "turns off journaling for speed." The video became so well-known in the engineering community that MongoDB engineers have cited it in conference talks as motivation for improving durability guarantees.
MongoDB's default write concern was "unacknowledged" until 2012¶
The original MongoDB driver default was "fire and forget" — writes were sent to the server with no acknowledgment of success. This meant applications could silently lose data without knowing it. The default was changed to "acknowledged" (w:1) in November 2012 with the introduction of the new CRUD API, but many existing applications continued running with the old default.
A single MongoDB collection held over 1 billion documents at Craigslist¶
Craigslist was an early and notable MongoDB adopter, using it to archive over 1 billion classified postings. At the time (around 2011), this was considered one of the largest MongoDB deployments. The document model was a natural fit for classified postings, which had varying fields depending on category.
MongoDB's WiredTiger storage engine came from a $300 million acquisition target¶
WiredTiger, which became MongoDB's default storage engine in version 3.2 (2015), was originally an independent company. MongoDB acquired WiredTiger in 2014. The engine, created by Keith Bostic and Michael Cahill, replaced the original MMAPv1 engine that used memory-mapped files and was notorious for database-level locking.
The "BSON" format adds overhead that surprises many developers¶
MongoDB stores data in BSON (Binary JSON), not JSON. BSON includes type information and length prefixes, which makes it larger than equivalent JSON for small documents. A simple {"a": 1} is 7 bytes in JSON but 16 bytes in BSON. For large documents with binary data, BSON is more efficient, but the overhead on small documents has surprised many developers expecting space savings.
Replica set elections can cause 10-30 seconds of downtime¶
When a MongoDB primary node fails, the remaining secondaries hold an election to choose a new primary. This election process typically takes 10-30 seconds during which no writes can be accepted. Applications that do not handle the NotWritablePrimary error will experience failures during this window, which has caught many teams off guard during their first production failover.
MongoDB Atlas became a $1.5 billion annual revenue business¶
MongoDB's fully managed cloud service, Atlas (launched 2016), grew to account for over 65% of MongoDB Inc.'s revenue by 2023, exceeding $1.5 billion annually. This made MongoDB one of the most successful examples of an open-source company transitioning to a cloud service business model.