pgquarrel

Overview

pgquarrel is a free utility for comparing PostgreSQL schema definitions and producing commands to align a target with a source. It is a good fit for operators moving DDL changes between environments who want to scope comparisons and choose how SQL is emitted. Its usefulness depends on the objects involved: coverage is incomplete, and a newer source server than the target can make the generated file behave unexpectedly.

Key features

Instead of using pg_dump, pgquarrel connects to PostgreSQL servers and reads catalog metadata. It compares schemas, not stored data, and does not issue INSERT, UPDATE, DELETE, or COPY operations. That makes it appropriate for schema deployment, but not for migrating table contents.

Filters can limit comparisons to selected object types and include or exclude schemas by pattern. This gives deployment teams a way to keep unrelated schemas or object classes out of a change set. SQL goes to stdout by default; users can also write it to a file, request a summary, or emit the changes as one transaction. These controls suit scripted workflows, though the generated commands still warrant review before deployment.

Support spans many PostgreSQL object types, but is partial for numerous types and complete for others. Inheritance and roles are notable omissions, and pgquarrel does not cover every PostgreSQL object. It is therefore a focused diff tool, not a guarantee that every schema difference will be represented.

Compatibility also needs attention: output may not work as expected when the source PostgreSQL version is newer than the target. The project is distributed as source through GitHub and can be cloned from its repository. It is BSD-3-Clause licensed, and version 0.7.0 is the latest release; its release notes mention fixes to Windows, Debian/Ubuntu, and FreeBSD builds. A public GitHub issues page handles bug reports and feature requests.

Pricing

pgquarrel is free: its sole plan costs nothing and is BSD-3-Clause licensed. There is no paid tier or free trial to weigh against it. The trade-off is not a feature cap tied to a subscription; it is the limits of object coverage and version compatibility.

Platforms

pgquarrel is listed for Linux, Windows, and self-hosted use. It is a single-engine tool for PostgreSQL, so it is not a fit for teams seeking one schema comparison workflow across different database engines.

Who it's for

Choose pgquarrel when you need a no-cost way to compare PostgreSQL DDL and generate changes for testing, staging, or production, especially when selective object and schema filters help define a deployment. Look elsewhere if your change sets rely on inheritance, roles, unsupported object types, or compatibility across a newer source and older target version.

Pros and cons

• Pros: Direct catalog access avoids dependence on pg_dump, and schema-pattern and object-type filters help keep comparisons focused.
• Pros: Stdout, file, summary, and single-transaction output options provide useful control for command-line deployment workflows.
• Pros: Free, BSD-3-Clause software is available as source, with a public channel for issues and feature requests.
• Cons: Partial support and gaps including inheritance and roles mean some schema changes will not be covered.
• Cons: Generated output can be unreliable when the source server version is newer than the target, requiring particular care in mixed-version deployments.
• Cons: It handles schema definitions only, so data migration requires another tool.

Alternatives

For another free PostgreSQL schema-diff tool, apgdiff is a straightforward alternative, with Linux, macOS, and Windows support. dbForge Studio for PostgreSQL is worth considering if you want a broader PostgreSQL workspace: its Express plan includes code completion, formatting, query history, a visual data editor, and import and export, and it offers a free plan and trial.

Skeema may suit teams looking for a free Community tier with tables, stored procedures and functions, and 18 linter checks; its Plus plan costs $124 a month. sqldef is another free, open-source CLI option for Linux, macOS, self-hosted, and Windows environments. For a broader comparison, see Database Schema Comparison Tools.

Verdict

pgquarrel is a sensible choice for teams deploying PostgreSQL schema changes who value selective comparisons and configurable SQL output without a license cost. Its main reason to choose is that focused, free workflow; its main reason to look elsewhere is incomplete object support, compounded by the source-newer-than-target version caveat. Use it where the schema objects and server versions fit, and choose another tool when complete coverage or cross-engine support matters.