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Synthetic Test Data

Faster CI/CD Pipelines, Fewer Broken Test Fixtures

If your team runs integration tests against PostgreSQL, you've probably felt the pain of database seeding: fragile scripts, broken foreign keys after migrations, and test data that never looks like reality. This guide explains why test data generation becomes hard as schemas grow — and how synthetic test data helps teams ship faster with more reliable CI/CD pipelines.

Seedfast is a PostgreSQL test data generator designed for teams that want synthetic data that stays valid as the schema evolves, without copying production records or maintaining brittle mock data scripts. It uses AI to plan constraint-aware datasets while applying privacy-focused handling of credentials and metadata.

Why PostgreSQL database seeding gets hard (fast)

Referential integrity isn't optional

When a dataset breaks relationships, database tests stop reflecting real application behavior. Foreign key errors, missing dependencies, or uniqueness collisions quickly turn test runs into debugging sessions — not of your product, but of your test fixtures.

Migrations are the silent fixture-killer

Each migration can change what "valid data" means: new NOT NULL fields, tighter CHECK constraints, additional UNIQUE rules, or new tables in dependency chains. Handwritten seed scripts and fake data generators often fail because they encode assumptions the schema has already outgrown.

CI/CD and test automation require predictability

Modern test automation loops create and refresh environments constantly: PR workflows, nightly runs, regression suites, and migration testing. Whether you're seeding a dev environment, staging database, or ephemeral test database, the process must be predictable — or your pipeline slows down and flakiness becomes normal.

What synthetic test data means (in practice)

Synthetic test data is generated from scratch to match your schema rules and relationships — rather than copied from production or maintained as brittle mock data scripts. Unlike traditional fake data generators, good synthetic datasets are:

  • Valid — all database constraints are satisfied

  • Connected — foreign key relationships are preserved

  • Safe — no production records required

Seedfast focuses on producing production-like relational structure by using schema metadata and existing data patterns as the source of truth for what "valid" looks like in your PostgreSQL database.

The Seedfast approach: constraint-aware test data generation

To generate test data that actually works, Seedfast analyzes your PostgreSQL database — both the schema structure and existing data patterns — then shares a minimal, derived description with an AI provider. This gives the AI enough context to understand relationships, constraints, and data patterns to propose coherent synthetic datasets for your database testing needs.

What may be included in the planning context

Depending on the run and your configuration, the test data generation context can include:

  • Table names (e.g., schema.table_name)

  • Column names and data types

  • NOT NULL / nullable constraints

  • Max length for varchar fields

  • Foreign key relationships

  • UNIQUE and CHECK constraints

  • Patterns derived from existing data (to understand implicit constraints)

The goal is to share what's necessary for planning valid synthetic test data — not to export your actual database contents or secrets.

Scope feedback (approve/reject + free-form instructions)

Seedfast may ask you to confirm what should be included in scope. Your approve/reject choices can be used as part of the planning context to ensure the generated test data matches what you actually want to seed.

You can also provide free-form scope instructions — for example: "exclude analytics tables", "seed only onboarding entities", "prioritize billing flows", or "keep datasets small but realistic." This makes it easier to align the synthetic dataset with your integration testing goals.

Data handling and privacy in test data generation

Two questions matter most when evaluating test data generation tools: (1) Do you send secrets? and (2) What data reaches the AI provider? Seedfast is explicit about both.

Credentials are masked before transmission

Credentials are masked inside the CLI before any network transmission:

  • password=***

  • postgres://user:pass@host becomes postgres://*:*@host

The same masking applies to API tokens.

What reaches the AI provider

To generate high-quality synthetic data, Seedfast sends schema metadata and existing data patterns to an external AI provider. This includes structural information and data samples needed for intelligent, constraint-aware generation. Seedfast is designed to share what's necessary for accurate test data generation — while keeping your database credentials out of the AI context entirely.

Best practices: PostgreSQL test data for CI/CD and integration testing

1) Treat test data as part of your build contract

When your schema changes, your database seeding strategy must keep up. Make it normal for schema changes to trigger refreshed test data generation — instead of spending days chasing failing pipelines.

2) Seed for workflows, not for tables

Useful test datasets are shaped by real workflows:

  • Onboarding flows need realistic organizations/users/projects relationships

  • Billing flows need consistent plans/subscriptions/invoices chains

  • Reporting needs event-style rows with believable timestamps and volumes

3) Stay constraint-aware

Valid test data comes from respecting the schema rules: required fields, uniqueness rules, relationship chains, and check constraints. If these aren't consistently satisfied in your mock data, you'll end up back in script-land.

Takeaway

PostgreSQL database seeding shouldn't be a fragile pile of scripts that breaks after every migration. If you want reliable integration tests and faster CI/CD, you need synthetic test data that stays valid as your schema evolves — without inheriting the risk and overhead of production copies.

Seedfast is built for that workflow: constraint-aware test data generation, privacy-focused handling of credentials and metadata, and synthetic datasets that respect both your schema and existing data patterns. It's a modern PostgreSQL test data generator for teams who value database testing that actually works.