Parse's MongoDB deployment was definitely not the largest by a longshot. Not even top 10.
They had the largest number of databases on a single replica set for sure, but largest in terms of cluster size or data size? No way.
They had the largest number of databases on a single replica set for sure, but largest in terms of cluster size or data size? No way.
160 shards = 160 replica sets, and is already larger than Parse.
I worked on building a feature that allowed Parse to list that many databases (it had response that does not fit in the document size limit of 16mb -- requiring multiple cursors, command cursors).
I am a collaborator on the parse-server project, love the Parse team, respect what they built, and have no incentive to deceive you.
I worked at MongoDB for 4 years in various roles, consulting, engineering, etc and saw all sorts of deployments of various shapes and sizes.
I've changed the passage to "one of the greatest". As in the disclaimer above the article, I'm mainly presenting assertions by Parse engineers, who were very sure about being the largest MongoDB user in terms of cluster size.