Technically yes, but you can use elasticsearch as a distributed key-value store. I use it in production and it works amazingly well for me. Yes, searches may return stale data (one second old by default) but that is not much of a problem in my app.
EDIT: Color me surprised. I didn't see it mentioned at all in the ElasticSearch docs or in their Github repo, but apparently this is a fairly popular thing to do.
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