Does batching writes support multiple writing values of the same key?

[bh4rtp2023]

I am doing a batch chaincode writes. In some of these batching writes, it needs to update values of the same key.
Is this supported by batching chaincode writes feature? Thanks.

[remo-lab]

Yes, this is supported, but with an important caveat.

Within a single transaction, Fabric only keeps one write per key in the write-set. If your batch logic updates the same key multiple times, each PutState simply overwrites the previous value in memory, and only the final value is committed when the transaction is validated.

So this works fine as long as you don’t rely on intermediate values being persisted. If you need to preserve multiple updates, you’ll need to encode them into the value, use separate (for example, composite) keys, or compute the final value first and write once.

Hope that helps — happy to clarify if needed.