NoSQL with key/value/value

Question

I'm looking for a NoSQL database with the simplicity and speed of kyoto cabinet that allows me to store 2 values per key. Also with a Java API. I looked at http://nosql-database.org/ but am a bit overwhelmed by the number of choices so I was hoping that people here could advise me (preferrably open source as my application will be open source as well).

What I'm trying to achieve is: store a data-"value" + a count-value with a hash-key. To elaborate:

• I have a table with an index-value (0...infinite) where each index maps to a hash. multiple indexes can map to the same hash
• then I have a table where the key (that same hash as the index-table) maps to a blob of data
• now to determine if I can throw away the hash/data pair, I need to determine how many index-values map to a hash. as iterating through the index/hash-table takes too long (millions of records and kyoto cabinet has no direct commands for doing so), I now have a seperate table where each hash maps to a value indicating the use-count
• I would like to store this count in the hash/data-table to prevent another look-up (which cause a diskseek)

Any suggestions?

Answer 1

0x69's idea point me in the right direction.

Now my hash + count and hash + data are in the same table, but the hash for count is prefixed with 'c' and the data-one with a 'd'.

This method enabled me to use kyoto cabinet for it. KC has transaction-support which takes away all the hassle of implementing journalling myself.