Schema coverage scan: What a scan does and does not prove

The denominator is the check. "Missing from 3" is not something you can act on — three of five is a mistake, three of forty is a rollout half done.

• A database that could not be read is counted as failed and is absent from the findings, not counted as missing. "Not there" and "not looked at" are different answers.
• A scan that finds nothing observed nothing differing across the databases it read. That is not a claim that the group is consistent, and no partial scan can establish that.
• A scan always re-reads every database, even ones already cached. An answer assembled from a three-week-old copy is not an observation.