Select distinct secondary key values in BerkeleyDB JE

Question

I have a Berkeley DB JE setup using the DPL.

I have a secondary key field which is a string, and I would like to retrieve all distinct values for this key. No additional fitlering is required, I simply want all the distinct values.

I could iterate over all entries and add values to sets, but this seems very inefficient as I have on the order of 10s of values from hundreds of thousands of rows.

Answer 1

If you just need the distinct keys (not the distinct entities), you can do this by calling SecondaryIndex.keys and then calling EntityCursor.nextNoDup to iterate through the unique values.

I recommend posting questions on Berkeley DB Java Edition to its OTN forum.

--mark