Atlas vs SSDT (SQL Server Data Tools): Why Modern Teams Choose Atlas

SQL Server Data Tools (SSDT) has been the go-to solution for defining database projects in Visual Studio, building them into DACPAC files, and deploying them via the SqlPackage CLI. For teams deeply embedded in the Microsoft ecosystem, it's familiar and well-integrated.

But SSDT was designed before Infrastructure as Code became standard, before GitOps, before teams began managing databases alongside Kubernetes and Terraform. Microsoft has been modernizing the toolchain with SDK-style SQL projects (Microsoft.Build.Sql), but as of late 2025, this remains in preview.

Atlas approaches database schema management differently. It's cross-platform (Windows, macOS, Linux), supports both declarative and versioned workflows, and was built from the ground up for modern CI/CD pipelines. This document explores the key differences to help you decide which tool fits your team.

Full Disclosure

This document is maintained by the Atlas team and was last updated in December 2025. It may contain outdated information or mistakes. For SSDT's latest details, please refer to the official Microsoft documentation.

Quick Comparison

Feature / Capability	Atlas	SSDT (SQL Server Data Tools)
Workflows	Declarative (state-based) and versioned	State-based only (DACPAC deployment model)
Migration Planning	Automatic diff-based planning with policy-awareness and checks	Automatic generation; plan can be scripted for review but lacks policy checks
Rollback / Down Migrations	Dynamic, state-aware rollback with safety checks	Not supported
Validation & Linting	Analyzers for destructive changes, table locks, naming conventions, and custom rules	Static analysis for T-SQL projects only
Testing Framework	Schema and migration tests that run locally and in CI/CD	SQL Server Unit Test projects in Visual Studio; no migration testing
Policy Enforcement	Diff policies, schema rules, deployment checks, and custom rules	Not available
CI/CD Integration	Native GitHub, GitLab, Azure DevOps, Bitbucket, CircleCI actions	Azure DevOps task; GitHub Actions via community samples; others require scripting
Kubernetes Integration	Official Operator with CRDs (AtlasSchema, AtlasMigration), Argo CD and Flux CD compatible	No official operator
Terraform Integration	Official provider (atlas_schema, atlas_migration)	No provider
Cloud Registry & Docs	Schema Registry, ERDs, schema statistics, deployment traces, drift monitoring, and PR checks	Not available
Multi-tenant Migrations	DB-per-tenant and schema-per-tenant with controlled rollout	Not supported
Database Support	PostgreSQL, MySQL/MariaDB, SQL Server, Oracle, ClickHouse, SQLite, CockroachDB, TiDB, Redshift, Spanner, Snowflake, and more	SQL Server and Azure SQL Database only
Drift Detection	Continuous monitoring with alerts and detailed diffs	One-time DriftReport via SqlPackage CLI
ORM Integration	Load schemas from Entity Framework, Hibernate, GORM, Django, SQLAlchemy, and generate migrations	Not available
Static/Seed Data	Data migrations with full linting and testing	Post-deploy scripts with MERGE statements (manual maintenance)
Database Security as Code	Declarative roles, users, grants, and permissions with automatic diffing	Included in DACPAC model; no dedicated diffing, drift detection, or policy enforcement
Declarative Data Management	Define seed data in desired state; Atlas computes minimal diffs	Post-deploy scripts with MERGE statements; manual, not declarative

Declarative and Versioned Workflows

SSDT is strictly state-based. Schemas are defined in a Visual Studio project, and during deployment, SSDT compares the target database to that model and generates a deployment plan. The process is automated, but users don't control how the diff is computed - and sometimes the generated SQL can be surprising. Renaming a column? SSDT might drop and recreate the table.

Atlas supports two workflows: declarative and versioned. In declarative mode, you describe your desired schema in any source format - HCL, SQL, or your ORM - and Atlas computes a migration plan by diffing against the live database. In versioned mode, you run atlas migrate diff to generate migration files that you can review, edit, and commit to version control.

The key difference: Atlas keeps you informed. Atlas always shows you the planned SQL before execution, so a human can review and approve it. In CI, linting runs automatically to catch destructive changes or table locks before they reach production. If you need to edit a migration, Atlas will detect any drift between your custom plan and the desired state.

ORM Integration

For .NET teams using Entity Framework, Atlas can ensure that your C# models remain the source of truth while Atlas handles migration generation.

atlas migrate diff --env ef

Atlas loads your EF Core model, compares it to the migration directory, and generates the migration files. No need to maintain separate Visual Studio projects. The same works for Hibernate, GORM, Django, SQLAlchemy, Drizzle, and other ORMs.

Read more: ORM Integrations

Importing Existing Schemas

Atlas can inspect existing SQL Server databases and export them to schema files in SQL or HCL format. Once inspected, Atlas can organize the output per schema, per object type, or per object. This enables managing database schemas as real programmatic code.

The result is a structured directory with each object in its own file:

schema/
├── tables
│   ├── profiles.sql
│   └── users.sql
├── functions
│   └── get_user.sql
├── types
└── main.sql

To get started, see the Export Database Schema to Code guide, or run one of the following commands:

# Export to SQL format
atlas schema inspect -u "sqlserver://localhost:1433?database=mydb" --format '{{ sql . | split | write "schema" }}'

# Export to HCL format
atlas schema inspect -u "sqlserver://localhost:1433?database=mydb" --format '{{ hcl . | split | write "schema" }}'

Migration Safety and Linting

When you publish a DACPAC, SSDT generates a deployment script, but it doesn't analyze whether that script is safe. It won't warn you that an ALTER TABLE will lock the table for minutes, or that dropping a column will destroy data.

Atlas includes a suite of analyzers that run during linting. These detect destructive changes like dropping tables or columns, operations that acquire long-held locks, naming convention violations, and data-dependent changes that might fail based on existing data.

Atlas policies are configured in atlas.hcl and cover different stages:

• Diff policies: Control how migrations are planned (e.g., require concurrent index creation)
• Schema policies: Enforce rules on the schema itself (e.g., naming conventions, required indexes)
• Lint policies: Catch dangerous patterns in migration files (e.g., destructive changes, table locks)
• Deployment policies: Gate production deployments with approval workflows

atlas.hcl

diff {
  concurrent_index {
    create = true
  }
}

lint {
  destructive {
    error = true
  }
  naming {
    match   = "^[a-z_]+$"
    message = "Table names must be lowercase with underscores"
  }
}

Read more: Migration Analyzers, Migration Safety

Down Migrations and Rollback

SSDT doesn't support rollback. If a deployment fails or causes issues, reverting requires manual intervention - writing and testing revert scripts by hand.

Atlas takes a fundamentally different approach. Instead of requiring pre-written rollback scripts, the atlas migrate down command computes rollback plans dynamically based on the actual state of the database:

1. Inspects the current database state
2. Determines what migrations were applied (fully or partially)
3. Performs drift detection to verify the schema matches the expected state
4. Computes the exact SQL statements needed to reach the target version
5. Validates the plan with automatic safety checks

# Revert the last 2 migrations
atlas migrate down --env prod 2

# Preview what would be reverted
atlas migrate down --env prod --dry-run

# Revert to a specific version
atlas migrate down --to-version 20240301000000 --env prod

Handling Partial Failures

For databases with transactional DDL (PostgreSQL, SQLite, SQL Server), Atlas wraps the entire rollback in a transaction - either all statements succeed, or none are applied.

For databases without transactional DDL (MySQL, MariaDB), Atlas executes statements one-by-one, recording progress after each successful step. If a failure occurs mid-rollback, re-running Atlas continues from where it stopped.

Pre-Migration Checks

Before executing destructive operations, Atlas runs pre-migration checks. For example, before dropping a table, Atlas verifies it's empty:

-- checks before reverting version 20240305171146
  -> SELECT NOT EXISTS (SELECT 1 FROM `logs`) AS `is_empty`
-- ok (50.472µs)

-- reverting version 20240305171146
  -> DROP TABLE `logs`
-- ok (53.245µs)

If the check fails, the rollback is aborted, preventing unintended data loss.

Read more: Down Migrations, The Myth of Down Migrations

CI/CD and GitOps

Atlas provides first-party integrations across the CI/CD ecosystem, supporting migration planning, linting, applying, and rollback. When a PR is opened, Atlas posts comments with the planned SQL and linting results. The Kubernetes Operator manages schema state as a first-class resource, and the Terraform Provider enables managing schemas alongside infrastructure:

GitHub Actions

CI/CD pipelines with GitHub Actions

GitLab CI

GitLab CI/CD components

Azure DevOps

Azure Pipelines integration

CircleCI

CircleCI Orbs integration

Bitbucket

Bitbucket Pipes integration

Terraform

Atlas Terraform Provider

Kubernetes

Atlas Operator with CRDs

Argo CD

GitOps with Argo CD

Atlas Cloud provides deployment traces - end-to-end visibility into how migrations progress through environments, tracking when and where each version was applied, which databases were affected, and whether executions completed successfully.

Beyond SQL Server

SSDT only works with SQL Server and Azure SQL Database. If your organization uses PostgreSQL for one service and SQL Server for another, you need completely different tooling for each.

Atlas supports all major databases with the same workflows, policies, and CI/CD integrations. To get started, visit the database guides or click on one of the databases below:

PostgreSQLMySQLMariaDBSQL ServerSQLiteOracleClickHouseRedshiftSpannerSnowflakeDatabricksDSQLSee all →

Testing Migrations

Atlas provides dedicated testing commands for both schemas and migrations. Tests are defined in HCL files with SQL assertions, run against a dev database, and integrate with CI/CD pipelines.

Schema Tests

Test schema logic like functions, triggers, and constraints:

schema.test.hcl

test "schema" "check_email_format" {
  parallel = true
  assert {
    sql = "SELECT validate_email('user@example.com')"
  }
  catch {
    sql = "SELECT validate_email('invalid')"
    error = "Invalid email format"
  }
}

atlas schema test --env dev

Migration Tests

Test data migrations by seeding data and verifying outcomes:

migrate.test.hcl

test "migrate" "20240613061102" {
  migrate {
    to = "20240613061046"
  }
  exec {
    sql = "INSERT INTO users (name) VALUES ('Ada Lovelace')"
  }
  migrate {
    to = "20240613061102"
  }
  exec {
    sql = "SELECT first_name, last_name FROM users"
    output = "Ada, Lovelace"
  }
}

atlas migrate test --env dev

Read more: Testing Schemas, Testing Migrations

Multi-Tenant Deployments

SaaS applications often use database-per-tenant or schema-per-tenant architectures. With SSDT, you'd need to deploy to each database individually - hundreds or thousands of separate deployments.

Atlas supports multi-tenant migrations natively. Define tenant groups, and Atlas plans and applies schema changes across all of them in a single operation. Changes can be rolled out gradually, monitored for issues, and paused or rolled back if problems arise.

Read more: Database-per-Tenant Guide

Drift Detection and Schema Monitoring

SqlPackage has a DriftReport action that generates an XML report comparing two schemas. It's a one-time operation you run manually.

Atlas provides both CLI-based checks and continuous automated monitoring. The CLI check can run in CI with native integrations for GitHub Actions, GitLab CI, CircleCI, Bitbucket Pipelines, and Azure DevOps:

# Check if production matches expected schema
atlas schema diff \
  --from "sqlserver://user:pass@prod:1433?database=app" \
  --to "file://schema.sql" \
  --dev-url "docker://sqlserver"

Atlas Schema Monitoring provides continuous, automated drift detection. It compares your database schema with the expected state in real-time with minimal performance impact. When drift is detected, Atlas provides instant alerts via Slack or webhooks, visual ERD diffs showing exactly what changed, and an SQL plan to remediate the drift.

Beyond drift detection, Atlas Schema Monitoring provides:

• Live schema visibility with auto-generated ER diagrams and documentation
• Schema statistics including table sizes, row counts, and index usage
• Schema changelog tracking all changes over time
• Flexible deployment via agent-less (GitHub Actions, GitLab CI) or agent-based setups
• Monitoring as Code - define your monitoring setup in HCL and deploy via CI/CD

Read more: Schema Monitoring

Working with AI Tools

AI coding assistants like GitHub Copilot and Cursor are great at writing application code, but database migrations are trickier. The generated SQL needs to be deterministic, respect your policies, and not accidentally drop production data.

Atlas bridges this gap. AI tools can edit your schema files, and Atlas handles the rest: generating safe migrations, validating them against policies, and running tests. The atlas migrate diff command ensures that whatever the AI suggests gets translated into a proper, linted migration.

Atlas also includes a built-in chat assistant that can explain migration errors, suggest safer patterns, and generate schema tests.

GitHub Copilot Instructions

Configure GitHub Copilot with Atlas-specific instructions.

Cursor Instructions

Set up Cursor with Atlas-specific rules.

Claude Code Instructions

Set up Claude Code with Atlas-specific instructions.

OpenAI Codex Instructions

Set up OpenAI Codex with Atlas-specific instructions.

Database Security as Code

Managing database access control (roles, users, grants, and permissions) is a critical responsibility, especially in regulated industries.

SSDT includes security objects (users, roles, permissions) in the DACPAC model and can deploy them alongside schema changes. However, there is no dedicated security diffing, drift detection, or policy enforcement. Security objects are treated the same as any other database object - deployed through the same opaque diff process without specialized visibility or governance.

Atlas provides Database Security as Code. Teams define their desired security posture (roles, users, grants, and permissions) declaratively alongside their schema in HCL or SQL. Atlas diffs the current security state against the desired state and plans the required changes automatically. Security changes flow through the same CI/CD pipeline as schema changes - linted, reviewed, and deployed with full audit trails.

HCL

schema.hcl

role "app_reader" {
  login = false
}

role "app_writer" {
  login     = true
  member_of = [role.app_reader]
}

permission {
  to         = role.app_reader
  for        = table.users
  privileges = [SELECT]
}

permission {
  to         = role.app_writer
  for        = table.users
  privileges = [SELECT, INSERT, UPDATE]
}

SQL

schema.sql

CREATE ROLE app_reader;
CREATE ROLE app_writer;
ALTER ROLE app_reader ADD MEMBER app_writer;

GRANT SELECT ON dbo.users TO app_reader;
GRANT SELECT, INSERT, UPDATE ON dbo.users TO app_writer;

Beyond defining and diffing security state, Atlas lets teams enforce custom security policies using its schema rules engine.

This completes the security lifecycle: define → diff → enforce → audit. For an overview of how Atlas supports database governance end-to-end, see the Database Governance use case.

Declarative Data Management

Applications often depend on reference data (lookup tables, feature flags, configuration values) that must exist for correct operation.

SSDT handles seed data through post-deployment scripts containing MERGE statements. These scripts are manually maintained, run after every deployment, and have no diffing or upsert logic built in. The developer writes the full MERGE/INSERT logic and is responsible for keeping it in sync with the data model.

Atlas provides Declarative Data Management. Teams define seed data directly in their desired state file using HCL data blocks or SQL INSERT statements. Atlas computes the minimal set of INSERT, UPDATE, or DELETE statements needed to bring the data to the desired state. Sync modes include UPSERT and REPLACE. Data is versioned alongside the schema and deployed through the same CI/CD pipeline.

HCL

schema.hcl

table "countries" {
  schema = schema.public
  column "id" {
    type = int
  }
  column "code" {
    type = varchar(2)
  }
  column "name" {
    type = varchar(100)
  }
  primary_key {
    columns = [column.id]
  }
}

data {
  table = table.countries
  rows = [
    { id = 1, code = "US", name = "United States" },
    { id = 2, code = "IL", name = "Israel" },
    { id = 3, code = "DE", name = "Germany" },
  ]
}

SQL

schema.sql

CREATE TABLE countries (
    id INT PRIMARY KEY,
    code VARCHAR(2) NOT NULL,
    name VARCHAR(100) NOT NULL
);

INSERT INTO countries (id, code, name) VALUES
    (1, 'US', 'United States'),
    (2, 'IL', 'Israel'),
    (3, 'DE', 'Germany');

To learn more, see the HCL or SQL data management docs.

Summary

SSDT has served the SQL Server community well for many years. It's mature, integrated with Visual Studio, and familiar to .NET developers. For teams that live entirely within the Microsoft ecosystem and don't need advanced safety features, it gets the job done.

Atlas offers a more modern approach: schema-as-code with automatic migration planning, linting that catches issues before they hit production, rollback that actually works, and integrations with the tools teams use today - Kubernetes, Terraform, GitHub Actions, and AI assistants. For teams adopting GitOps, managing multiple databases, or looking for stronger safety guarantees, Atlas provides capabilities that SSDT's toolchain doesn't offer.