Postgres

Declare the plugin, then point a DATABASE statement at it:

PLUGIN postgres (
  source  = 'NSchema.Postgres',
  version = '[5.0,6.0)'
);

DATABASE postgres (
  connection_string = '',
  command_timeout = 30
);

The label (postgres here) is yours to choose; the DATABASE statement selects the plugin by referencing it. The package is resolved and locked by init and restored on first use — for CLI use you don’t install it by hand.

Attributes

Attribute	Type	Description
connection_string	string	The connection string used to reach the database. Best supplied via the environment (see below).
username	string	The username, supplied separately from the connection string. Overrides any user embedded in it.
password	string	The password, supplied separately from the connection string. Overrides any password embedded in it.
command_timeout	integer	The command timeout, in seconds.

The connection string

The connection string is a secret. Supply it through an environment variable rather than committing it:

export NSCHEMA_DATABASE_CONNECTION_STRING="Host=localhost;Database=app;Username=postgres;Password=postgres"

NSCHEMA_DATABASE_CONNECTION_STRING takes precedence over a connection_string set in the statement. A connection_string in the statement is fine for a local database, but keep real secrets in the environment.

Credentials supplied separately

When a secret store (e.g. AWS Secrets Manager) injects the database username and password out of band, keep only the non-secret host/port/database in the connection string and supply the credentials on their own:

export NSCHEMA_DATABASE_CONNECTION_STRING="Host=db.internal;Port=5432;Database=app"
export NSCHEMA_DATABASE_USERNAME="$DB_USER"
export NSCHEMA_DATABASE_PASSWORD="$DB_PASSWORD"

These override any user/password embedded in the connection string. The base connection string is applied first, then the discrete overrides are layered on top. See Environment variables.

Dialect and equivalence

The SQL dialect is determined by the provider, so there is nothing to configure. NSchema’s canonical types are translated to PostgreSQL’s spelling on output, and any opaque expressions in DEFAULT / CHECK / etc. are passed through verbatim.

The provider also registers equivalence rules for comparison, so spellings the catalog and your project may legitimately disagree on (bool against boolean, a default the server has rewritten with a cast) compare equal in either direction and don’t show up as drift.