Read Concern "snapshot" for snapshot isolation outside explicit transactions

TL;DR: I a previous post I explained why Why isn't "majority" the default read concern in MongoDB. If you’re used to SQL databases, you’ll likely prefer the snapshot read concern, which guarantees all rows are read from the same snapshot. Alternatively, run your operations in an explicit transaction, as transactions are ACID. With majority, you avoid dirty or uncommitted reads because you only see data acknowledged by a majority. However, a scan can yield while the majority state advances, so some rows may come from a newer majority snapshot. By default, MongoDB’s consistency boundary is the document—similar to an aggregate in domain‑driven design. For multi‑document consistency, use explicit transactions or the snapshot read concern. This is MongoDB’s tunable consistency model, whose defaults often suit event‑driven architectures more than traditional SQL workloads. To illustrate this, here’s a demo. I start by setting up the collection, the document count, and other parameters: const