Postgres

Built in. Scans tables, views, materialized views, foreign tables and partitioned tables.

Capability
Reads data	No
Writes metadata back	No (reports only)
Reads sample values	No

Connecting

Any libpq connection string works, as a URI or as key-value pairs:

export QUORLO_DSN=postgresql://quorlo_reader@db.internal:5432/warehouse
quorlo scan

Standard libpq environment variables and files (PGPASSWORD, .pgpass, PGSSLMODE, ...) apply as usual.

Permissions

Quorlo reads only the system catalogs (pg_class, pg_attribute, pg_constraint, ...), which every role can read by default. It does not need SELECT on your tables. A dedicated login role with no other grants is enough:

CREATE ROLE quorlo_reader LOGIN PASSWORD '...';

What it reads

Metadata	Source
Schemas and their comments	pg_namespace
Tables, views and their kind	pg_class
Columns, types, nullability, defaults	pg_attribute, pg_attrdef, format_type()
Table and column comments	obj_description(), col_description()
Primary keys, unique constraints, foreign keys	pg_constraint
Approximate row count	pg_class.reltuples (planner statistics)

System schemas (pg_catalog, information_schema, pg_toast, temporary schemas) are skipped. Partitions are skipped in favour of their partitioned parent table.

Each schema costs exactly three queries (tables, columns, constraints), plus one for the schema list, however many tables it has. Schemas stream one at a time, so memory stays bounded by the largest schema. A scan prints its query count, for example fetch 0.02s (7 queries) for two schemas.

All of a scan's queries run in one read-only REPEATABLE READ transaction, so they see a single consistent snapshot. A table created or altered while the scan runs is not half-seen.

Row counts

The row count is the planner's estimate from the last ANALYZE or autovacuum. It is empty for a table that has never been analyzed. Quorlo never counts rows.

Read-only, enforced by the server

The connection is opened with psycopg's read_only = True, which makes every transaction READ ONLY. Postgres itself rejects any write, whatever query is sent. The connector refuses to start on a connection configured for writing.