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To visualize an existing PostgreSQL schema, use a database client’s ERD or diagram feature for a quick live view, or generate documentation or curate a smaller diagram when you need a shareable, focused explanation. An ERD shows tables and declared relationships; it may not show relationships that are not enforced by database constraints.
What a PostgreSQL schema diagram can—and cannot—show
A diagram turns database objects into a visual map. An entity-relationship diagram (ERD) typically represents tables as entities, columns as attributes, and declared foreign keys as connections. PostgreSQL schemas are namespaces that organize objects within a database; a database-level view can include objects from multiple schemas. See the PostgreSQL 18 documentation on schemas.
Do not assume a line between two tables means the tool inferred a business relationship. Unless a relationship is represented by a database constraint or otherwise added to the diagram, it may be absent. Conversely, a schema-only view can omit links to tables outside that schema, even when those links exist in the database.
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1. pgAdmin ERD tool: generate a diagram in your PostgreSQL administration client
pgAdmin’s ERD tool can create a diagram from a database, schema, or table. Use database scope when you want tables from all schemas represented with their foreign-key links. Use schema scope for a narrower view, but be aware that links to tables in other schemas are removed from that view. The distinction matters in databases where related tables are split across schemas.
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The tool can save diagrams, export an image, add notes, align tables automatically, and generate SQL from a design. It is a practical starting point if you already administer the database in pgAdmin and want a diagram without moving to another application. Read the pgAdmin ERD Tool documentation for its scope and operations.
2. DBeaver diagrams: explore a schema or build a selected-table view
DBeaver documents diagrams for existing tables and schemas, as well as custom diagrams that combine selected tables. Its diagram editor supports rearranging entities, changing displayed details, searching, generating SQL, and exporting or printing. That flexibility helps when a full schema view is too broad and you need a smaller diagram of related tables.
Diagrams are read-only by default. If you enable Edit mode, actions such as adding tables, columns, or foreign keys generate SQL that you can review and execute. Treat that as a route to proposed database changes, not as a reason to run generated SQL without review. Export formats and availability can vary by edition, so check the relevant details in the DBeaver diagram guide and its diagram operations documentation.
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3. DataGrip diagrams: visualize at data-source, schema, or table scope
DataGrip provides database diagrams for a data source, a schema, or an individual table. You can show or hide non-key columns and save a diagram as UML or PNG. This is a fit if DataGrip is already part of your database workflow and you want to move from browsing objects to a visual representation in the same environment. The DataGrip database diagrams documentation describes the available scopes and saving options.
4. SchemaSpy: generate browsable database documentation
SchemaSpy is a standalone application that generates browsable documentation from a database connection. Its project README describes a PostgreSQL connection workflow and output generated in a directory. This approach is more suited to documenting a database for browsing or sharing than to interactive exploration in a database-client canvas.
Connection setup and generated output depend on configuration. Consult the SchemaSpy project README for its PostgreSQL workflow; do not assume every generated diagram format or behavior will match your setup.
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5. Curate a manual or diagram-as-code view
A hand-curated diagram can explain one subsystem, workflow, or set of important relationships without trying to fit every object in a large database onto one canvas. Keeping a diagram’s editable source alongside other documentation can make it easier to maintain as the schema changes.
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For this route, select a tool and validate that it represents the PostgreSQL constraints and object types that matter to your readers. A diagram built from an imported or manually maintained schema representation is only as current and complete as that representation. Do not treat column-name similarity as proof of a relationship.
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| Approach | Input and scope | Useful output or interaction | Best fit |
|---|---|---|---|
| pgAdmin ERD | Existing database, schema, or table; database scope includes all schemas, while schema scope can omit cross-schema links. | Saved diagram, image export, notes, auto-alignment, and SQL generation. | Existing pgAdmin users who want a direct database-derived view. |
| DBeaver diagrams | Existing tables or schema, or a custom selection of tables. | Rearrangement, search, display controls, export or print; Edit mode produces SQL for review and execution. | Users who want to explore a broad schema or create a focused selection in a database client. |
| DataGrip diagrams | Data source, schema, or table. | Hide or show non-key columns; save as UML or PNG. | DataGrip users who want diagrams within their database-browsing environment. |
| SchemaSpy | PostgreSQL connection configured for documentation generation. | Browsable output generated in a directory. | Readers who need documentation to browse or share rather than a live diagram canvas. |
| Curated manual or diagram-as-code view | A selected subsystem or relationships represented in a maintained or imported schema description. | A focused, potentially version-controlled explanation; exact export and import capabilities depend on the chosen tool. | Teams that need a compact explanation rather than an exhaustive database map. |
Check freshness and scope
Determine whether the tool reads a live database or a separately maintained representation, then verify that the displayed schema reflects recent changes. Before sharing a diagram, establish whether it covers one table, one schema, selected tables, or the whole database. For pgAdmin in particular, database-level and schema-level ERDs have different cross-schema coverage.
Check relationship fidelity
Confirm that declared foreign keys appear and that the view includes the tables they reference. A diagram does not necessarily capture application-level relationships that are not declared as database constraints. If the diagram is meant to document those relationships too, identify them explicitly rather than presenting them as database-enforced facts.
Choose interaction or documentation
For live exploration, a database client such as pgAdmin, DBeaver, or DataGrip keeps the diagram close to database browsing. If you want generated, browsable documentation, SchemaSpy is a different kind of workflow. For DBeaver’s Edit mode, inspect generated SQL before execution.
Keep large diagrams readable
A complete database map can become difficult to scan. Start with the broadest view needed to understand scope, then create a table-centered, selected-table, or curated view for a specific question. Label the narrower view so readers know what it excludes; otherwise, a convenient diagram can be mistaken for a complete inventory.
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