> They were originally sequential and then they switched to even numbers for a while, then odd numbers. That sounds like they wanted to migrate to another clus

> They were originally sequential and then they switched to even numbers for a while, then odd numbers. That sounds like they wanted to migrate to another cluster, and wanted to have both clusters running at the same time (for testing) without risking an ID overlap, so they turned the least significant bit of the ID into a cluster identifier. The older cluster was 0 (even numbers), the new cluster was 1 (odd numbers).