We would like to store the time blocks arrive so that we can determine their arrival sequence.
CBlockIndex entries already have an nSequenceId, which may serve the same purpose. It not persisted, however, and set to 0 for all blocks on disk and incremented for each block received while the process is running.
What is the need for an arrival timestamp? Should it replace nSequenceId? Does it need to be persisted? Backfilled?