Battle key-value vaults

What key-value vault do you use in combat?

I borrowed the list from the site db-engines.com (by the way, a very curious site, I recommend), included all the databases with non-zero “popularity” from there. Do not mark the bases that just tried / interesting, but only those that are spinning and bring money to your company right now.

Please note: MongoDB is NOT a key-value repository, however you can vote for it, see “Document storage as key-value”.

Write, if you have forgotten some popular database (that is, the authors of the site db-engines.com forgot), I’ll add to the survey.
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Which storage key-value properties are important to you?

A motley bunch of requirements. Please thoughtfully walk through them. Note that many properties contradict each other, because half is aimed at functionality, and the other at performance, which generally contradict each other. Some properties are possible only with other properties or combinations, some are reinforced / weakened versions of each other, etc.

Items 2-6 describe some reasonable transaction properties (by the way, you may not need transactions at all: (for example, simple get and put on a key are not transactions yet), then don’t mark any of these items), items 7 -9 - the level of consistency of the properties specified above.

“Native client for Java / C / C ++ / C #” means the client for these languages ​​does not just form a request in the language in which the base is written, and goes to some IPC / JNI, but directly works with the base. In essence, this means that the base is written (including) in this language. Due to the presence of such pieces as Protocol Buffers, Thrift and Detailed, the base, generally speaking, can be written in several languages.

I 100% forgot some important properties, write in a personal, add to the survey.