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... back then, lots of projects were saying referential integrity was an operations problem. That was rubbish, and they knew it. Same for multimaster replication. Fortunately we're past that now. But I like MongoDB for its document model, not its service architecture (although it definitely gets the job done). This Monty is an interesting project, and I'm looking forward to future developments.

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Its document model is vanilla BSON on disk.

It possible to update the BSON without loading the entire document in the memory? I am curious how Mongo does updates.

It’s a memory mapped file. If you update a bool or number value it’ll rewrite just that. If you update anything else it’ll often have to rewrite the entire document due to variable size.

I assume when you say just that, it will write an entire page.

In practice yeah I guess.

But rewriting the document is more extensive, it might even have to be moved (because Mongo allocates certain number of bytes for it, and it might outgrow that).

That was true with MMAPv1. It's not since March 2015, when WiredTiger was introduced with MongoDB 3.0.

Thanks for the kind words !

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