Question

I store a column value in DB either as:

1. an empty byte array new byte[0]
2. an int value
3. a non-empty byte[]

On retrieval of the column value I retrieve it as a Bytebuffer & I need to detect whether it stored an integer, empty byte[], or non-empty byte[].

How do I detect looking at read Bytebuffer, what was stored in it among the above 3 possible options ?

Answer 1

You can’t, after all they are just a pile of bits. You need an external indicator. It can be either a second column or the first bit(s) of input.

If you loaded an empty buffer, empty byte[] was stored. If it’s not empty, check first bit (or byte for simplicity). Agree that some value indicates that the rest is byte[] while other value indicates encoded int. Of course prior to that you must also store that indicator.