http://www.linkedin.com/groups/Difference-between-elasticsearch-MongoDB-3393294.S.5887644059169730563
But you need to consider: Elasticsearch is an index/search engine not a database, there is also no inbuild security (like password protection or access rights). We tried a while to use it "as database", but the problem arrives when you have to update many fields (there is since a long time a request o support "update by query" on github) or when you want to change the schema/mapping - you need to delete the data or reindex the data, which can be a long process when you got many records.
上面三处红线，列出了Elasticsearch三个缺点，也是不能作为数据库的三点