PostgreSQL ERD Generator: Visualize Tables, ENUMs, and Foreign Keys

Why PostgreSQL Schemas Need Good Diagrams

PostgreSQL schemas often contain more than simple tables. Real projects use ENUM types, identity columns, schema-qualified names, JSON fields, array types, composite keys, generated columns, partial indexes, and foreign keys with cascading rules. A diagram helps the team understand all of that structure faster than reading DDL line by line.

A PostgreSQL ERD generator reads your DDL and creates an entity relationship diagram with tables, columns, primary keys, foreign keys, and constraints. The Erd Go SQL to ERD editor supports PostgreSQL-style schema definitions so you can paste DDL and inspect the model immediately.

PostgreSQL Features Worth Visualizing

When choosing a Postgres diagram workflow, make sure the tool understands the database features your application actually uses.

• Identity and serial columns. Primary keys such as SERIAL, BIGSERIAL, and GENERATED ALWAYS AS IDENTITY should be recognized as generated identifiers.
• Custom types. CREATE TYPE ... AS ENUM values should remain visible instead of being flattened into generic strings.
• Foreign keys. Inline REFERENCES and named table-level constraints both need to produce diagram relationships.
• Schema-qualified objects. Names such as billing.invoices and auth.users should remain understandable in the diagram.

Example PostgreSQL DDL

Paste this example into the editor to generate a PostgreSQL-flavored ERD:

CREATE TYPE order_status AS ENUM ('draft', 'paid', 'shipped', 'cancelled');

CREATE TABLE customers (
    id          BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
    email       TEXT NOT NULL UNIQUE,
    full_name   TEXT NOT NULL,
    metadata    JSONB DEFAULT '{}'::jsonb,
    created_at  TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE TABLE orders (
    id          BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
    customer_id BIGINT NOT NULL REFERENCES customers (id),
    status      order_status NOT NULL DEFAULT 'draft',
    total       NUMERIC(12, 2) NOT NULL CHECK (total >= 0),
    tags        TEXT[] DEFAULT ARRAY[]::TEXT[],
    created_at  TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE TABLE order_events (
    id          BIGSERIAL PRIMARY KEY,
    order_id    BIGINT NOT NULL REFERENCES orders (id) ON DELETE CASCADE,
    event_name  TEXT NOT NULL,
    payload     JSONB NOT NULL DEFAULT '{}'::jsonb,
    created_at  TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE INDEX idx_orders_customer_id ON orders (customer_id);
CREATE INDEX idx_order_events_order_id ON order_events (order_id);

The important relationships are customers → orders and orders → order_events. The custom enum, JSONB columns, arrays, checks, and indexes add implementation detail without hiding the core data model.

Postgres ERD Workflow

For teams using PostgreSQL, a SQL-first diagram workflow is usually the most reliable.

• Export or copy the current DDL from your migration files, schema dump, or pull request.
• Paste it into Erd Go to generate the diagram automatically.
• Move important tables into readable clusters such as auth, billing, catalog, and audit.
• Use the diagram during review to check missing foreign keys and confusing ownership boundaries.
• After the migration is approved, regenerate the ERD from the updated DDL so the diagram stays in sync.

References and further reading

• PostgreSQL: defining tables and database objects
• PostgreSQL: constraints, nulls, and referential actions
• Erd Go: SQL-to-ERD syntax and supported workflows