It is a database for when you read a lot and don't write too often; when a write might be pretty big but not frequent; when you don't want to write a database engine yourself (I.e. figure out what to write and when). And, especially, when corrupting the data would be a big problem.

And it is especially good on copy-on-write filesystems, because it is CoW itself.

It's a database for strictly exact-match lookups for very read-intensive workloads; think systems where the database only changes when the configuration changes, like email alias or domain lookups. It's very simple (a first-level hash table chaining to a second-level open-addressed hash table) and easy to get your head around, but also very limiting; an otherwise strict K-V system that uses b-trees instead of hash tables can do range queries, which you can build a lot of other stuff out of.

Most people would use Redis or SQLite today for what CDB was intended for; CDB will be faster, but for a lot of applications that speed improvement will be sub-threshold for users.

Yes, the modifications you need to support it are trivially obvious (literally just replace “4 bytes” with “8 bytes” everywhere in the spec) and have been implemented by a number of authors, some of which this page links to. I guess it’s nice that they’ve been “officially” acknowledged, though.

It'd never have crawled out of the new page with that title.

No, the title is much better as it is.

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