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javamapdb

How to use byte arrays as keys in MapDB

I have a use case where I'd like to use opaque byte[] as keys into a MapDb. I discovered this - Using a byte array as Map key - limitation quickly; and wonder which approach is recommended.

I'd rather not create a bunch of interim objects and serialization overhead, but it seems like ByteBuffer.wrap(my_bytes) is where Java is pointing me.

I'm hoping one of the core devs of MapDB can weigh in on this or a ByteBuffer JVM guru.

Solution

  • MapDB author here.

    It is possible to use byte[] without wrappers. There is Hasher which handles hashCode and equals methods for HTreeMap:

        Map map = db.createHashMap("map")
            .hasher(Hasher.BYTE_ARRAY)
            .keySerializer(Serializer.BYTE_ARRAY)
            .makeOrGet();