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PostgreSQL driver

  • Connection driver: pgsql
  • Minimum server version: PostgreSQL 18

The pgsql driver is what a PostgreSQL connection resolves to. It supplies the rules that judge a migration's SQL on this engine, the readers that answer questions about the live catalog, and the canonicalization that turns whatever the query builder emitted into one comparable form.

The version floor is a floor, not a target​

Below PostgreSQL 18 the driver does not resolve, and the run reports version_below_floor rather than checking anything. That is a deliberate refusal: the rules describe behavior older releases do not have, and applying them anyway would produce confident, wrong advice — the failure mode this package is built to avoid.

Above the floor, a rule that only applies to a version range says so through its own version window. The engine evaluates that window before the rule runs, so a rule can never fire outside the versions it was written for, and an unknown version produces a named undetermined finding instead of a silent pass.

What the driver never does​

It opens no transaction of its own, takes no lock, and writes nothing. Every rule reads a subject the capture layer already produced, and the catalog readers use catalog and statistics views only. A run against a production replica is safe by construction rather than by convention.