Why pgmi?#

pgmi takes a different approach to database deployments. This document explains when that approach makes sense—and when it doesn’t.

The core idea#

Most deployment tools work like this:

Your files → Tool decides order → Tool decides transactions → Database

pgmi works like this:

Your files → PostgreSQL temp tables → YOUR deploy.sql decides everything → Database

The difference: you write the deployment logic in SQL, not configuration.

A concrete example#

Suppose you need environment-specific deployment behavior:

• In development: drop and recreate everything
• In staging: run migrations only if checksums changed
• In production: require explicit approval for destructive changes

With traditional tools, you’d need:

• Multiple configuration files
• Framework-specific conditionals
• External scripts wrapping the tool

With pgmi, it’s just SQL:

-- deploy.sql
DO $$
DECLARE
    v_env TEXT := COALESCE(current_setting('pgmi.env', true), 'development');
    v_file RECORD;
BEGIN
    IF v_env = 'development' THEN
        -- Recreate everything
        EXECUTE 'DROP SCHEMA IF EXISTS app CASCADE';
        EXECUTE 'CREATE SCHEMA app';
    END IF;

    -- Always run migrations
    FOR v_file IN (
        SELECT path, content FROM pg_temp.pgmi_plan_view
        WHERE path LIKE './migrations/%'
        ORDER BY execution_order
    )
    LOOP
        RAISE NOTICE 'Executing: %', v_file.path;
        EXECUTE v_file.content;
    END LOOP;

    IF v_env = 'production' THEN
        -- Log deployment for audit
        INSERT INTO audit.deployments (deployed_at, env) VALUES (now(), v_env);
    END IF;
END $$;

No framework DSL. No YAML conditionals. Just PostgreSQL.

Your deploy.sql queries pg_temp.pgmi_plan_view (or pg_temp.pgmi_source_view) and uses EXECUTE to run files directly. The IF v_env conditional controls what SQL runs based on runtime conditions. See Session API .

When pgmi makes sense#

pgmi is a good fit when:

You need deployment logic beyond linear migrations.

• Conditional execution based on environment
• Custom ordering that isn’t alphabetical
• Multi-phase deployments with different transaction strategies

You want explicit transaction control.

• Some migrations need individual transactions (to allow partial progress)
• Some need a single transaction (all-or-nothing)
• Traditional tools make you choose one approach globally

Your team is fluent in SQL/PL/pgSQL.

• pgmi’s power comes from writing deployment logic in PostgreSQL’s native language
• If your team avoids SQL, pgmi’s advantage disappears

You’re building automation that needs predictability.

• Same inputs = same outputs, always
• The deployment plan is queryable data, not opaque framework state
• Clear success/failure signals via PostgreSQL exceptions

You deploy data files alongside schema.

• JSON configuration, XML reference data, CSV seed data — loaded and processed in the same transaction as your migrations
• Checksum columns in pgmi_source_view enable change detection — your deploy.sql can compare checksums against a tracking table to skip unchanged files (the advanced template does this automatically)
• See deploy.sql guide for data ingestion patterns

You target multiple cloud PostgreSQL providers.

• Same deploy.sql works on Azure Database for PostgreSQL, Amazon RDS, Google Cloud SQL, Citus, TimescaleDB, Neon, Supabase
• Native auth integration (Azure Entra ID, AWS IAM, Google Cloud SQL IAM) — no credential translation layer
• See Connections for the full connection architecture

You want fast iteration with disposable databases.

• pgmi deploy . --overwrite --force drops and recreates the database, then deploys from scratch
• Tests run inside the deployment transaction and roll back automatically
• Zero manual cleanup between iterations

When pgmi is overkill#

pgmi handles linear migrations out of the box (the basic template does exactly this). pgmi ships with two templates — basic, a small, explicit migration scaffold, and advanced, a large, editable reference system (metadata tracking, roles, RLS, API/MCP). Advanced is more complete, not more production — either can be production depending on your project. See Choosing a Template for the canonical comparison.

But consider simpler tools if:

You’ll never need anything beyond linear migrations. If you’re certain your deployments will always be “run these numbered files in order” with no conditionals, no custom transaction strategies, and no testing gates — Flyway or Liquibase have a shallower learning curve.

You prefer framework-managed complexity. Some teams prefer “the tool handles transactions” over “I control transactions.” That’s valid—pgmi requires you to think about transaction boundaries.

You need a large ecosystem. Flyway and Liquibase have GUI tools, IDE plugins, extensive third-party integrations. pgmi is CLI-focused.

You’re not on PostgreSQL. pgmi is PostgreSQL-only by design. It leverages PostgreSQL-specific features (temp tables, PL/pgSQL, savepoints). Multi-database support is not planned.

The tradeoffs#

For a deeper exploration of pgmi’s costs, see Trade-offs .

Design principles#

PostgreSQL is the deployment engine#

pgmi doesn’t implement migration logic in Go. It loads your files into PostgreSQL and lets PostgreSQL run your deployment script. This means:

• You can use any PostgreSQL feature: pg_advisory_lock, system catalogs, extensions
• Errors are PostgreSQL errors with standard SQLSTATE codes
• Debugging uses PostgreSQL tools you already know

Infrastructure, not orchestration#

pgmi provides:

• File discovery and loading into temp tables
• Parameter injection as session variables
• Optional metadata parsing (<pgmi-meta>) for execution ordering
• Preprocessor macro expansion (CALL pgmi_test())
• deploy.sql execution

pgmi does NOT decide:

• Transaction boundaries (you write BEGIN/COMMIT)
• Which files run (you query and filter pgmi_plan_view or pgmi_source_view)
• Retry logic (you use EXCEPTION blocks)
• Idempotency (you write IF NOT EXISTS, ON CONFLICT)

Your SQL remains portable#

Your migration files are valid PostgreSQL SQL—you can run them directly with psql. The optional <pgmi-meta> blocks live inside standard SQL comments (/* ... */), so they don’t break compatibility. pgmi parses them before SQL reaches PostgreSQL to configure file ordering and idempotency tracking — they’re metadata about your files, not executable syntax.

The pgmi-specific parts are deploy.sql (which queries session temp tables) and any <pgmi-meta> blocks you choose to add. If you later switch tools, your migration files work unchanged — strip the comment blocks and they’re plain SQL.

Comparison with other tools#

For detailed migration guides, see Coming from Other Tools .

Next steps#

• Getting Started — Your first deployment in 10 minutes
• Session API Reference — The temp tables and functions available to deploy.sql
• Coming from Other Tools — Migration guides from Flyway, Liquibase, etc.