public void incrementReferenceCount(final Txn<ByteBuffer> writeTxn, final ByteBuffer keyBuffer) {

        final ByteBuffer currValueBuffer = getAsBytes(writeTxn, keyBuffer)
                .orElseThrow(() -> new RuntimeException(LogUtil.message(
                        "keyBuffer {} not found in DB",
                        ByteBufferUtils.byteBufferInfo(keyBuffer))));

        try (PooledByteBuffer pooledValueBuffer = getPooledValueBuffer()) {
            ByteBuffer newValueBuffer = pooledValueBuffer.getByteBuffer();
            valueSerde.cloneAndIncrementRefCount(currValueBuffer, newValueBuffer);
            PutOutcome putOutcome = put(writeTxn, keyBuffer, newValueBuffer, true);
            if (!putOutcome.isSuccess()) {
                throw new RuntimeException(LogUtil.message("Put failed for keyBuffer {}",
                        ByteBufferUtils.byteBufferInfo(keyBuffer)));
            }
        }
    }
increments the reference count by one for the key represented by the valueStoreKeyBuf.
stroom-pipeline/src/main/java/stroom/pipeline/refdata/store/offheapstore/databases/ValueStoreMetaDb.java