Database Migrations

Database migrations are SQL statements that create, update, or delete your existing database schemas. They are a common way of tracking changes to your database over time.

Schema migrations

For this guide, we'll create a table called employees and see how we can make changes to it.

You will need to install the Supabase CLI and start the local development stack.

If a lock timeout error occurs, in your migration file, consider increasing your lock_timeout setting.

<StepHikeCompact.Step step={1}> <StepHikeCompact.Details title="Create your first migration file"> To get started, generate a new migration to store the SQL needed to create our employees table. </StepHikeCompact.Details>

<StepHikeCompact.Code>

supabase migration new create_employees_table

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

<StepHikeCompact.Step step={2}> <StepHikeCompact.Details title="Add the SQL to your migration file"> This creates a new migration file in supabase/migrations directory.

  To that file, add the SQL to create this `employees` table.
</StepHikeCompact.Details>

<StepHikeCompact.Code>

create table if not exists employees (
  id bigint primary key generated always as identity,
  name text not null,
  email text,
  created_at timestamptz default now()
);

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

<StepHikeCompact.Step step={3}> <StepHikeCompact.Details title="Apply your first migration"> Run this migration to create the employees table.

  Now you can visit your new `employees` table in the local Dashboard.
</StepHikeCompact.Details>

<StepHikeCompact.Code>

supabase migration up

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

<StepHikeCompact.Step step={4}> <StepHikeCompact.Details title="Modify your employees table"> Next, modify your employees table by adding a column for department. </StepHikeCompact.Details>

<StepHikeCompact.Code>

supabase migration new add_department_column

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

<StepHikeCompact.Step step={5}> <StepHikeCompact.Details title="Add a new column to your table"> To that new migration file, add the SQL to create a new department column. </StepHikeCompact.Details>

<StepHikeCompact.Code>

alter table if exists public.employees
add department text default 'Hooli';

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

<StepHikeCompact.Step step={6}> <StepHikeCompact.Details title="Apply your second migration"> Run this migration to update your existing employees table. </StepHikeCompact.Details>

<StepHikeCompact.Code>

supabase migration up

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

Finally, you should see the department column added to your employees table in the local Dashboard.

View the complete code for this example on GitHub.

Seeding data

Now that you are managing your database with migrations scripts, it would be great have some seed data to use every time you reset the database.

<StepHikeCompact.Step step={1}> <StepHikeCompact.Details title="Populate your table"> Create a seed script in supabase/seed.sql.

  To that file, add the SQL to insert data into your `employees` table.
</StepHikeCompact.Details>

<StepHikeCompact.Code>

insert into public.employees
  (name)
values
  ('Erlich Bachman'),
  ('Richard Hendricks'),
  ('Monica Hall');

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

<StepHikeCompact.Step step={2}> <StepHikeCompact.Details title="Reset your database"> Reset your database to reapply migrations and populate with seed data. </StepHikeCompact.Details>

<StepHikeCompact.Code>

supabase db reset

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

You should now see the employees table, along with your seed data in the Dashboard! All of your database changes are captured in code, and you can reset to a known state at any time, complete with seed data.

Diffing changes

This workflow is great if you know SQL and are comfortable creating tables and columns. If not, you can still use the Dashboard to create tables and columns, and then use the CLI to diff your changes and create migrations.

<StepHikeCompact.Step step={1}> <StepHikeCompact.Details title="Create your table from the Dashboard"> Create a new table called cities, with columns id, name and population.

  Then generate a [schema diff](/docs/reference/cli/supabase-db-diff).
</StepHikeCompact.Details>

<StepHikeCompact.Code>

supabase db diff -f create_cities_table

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

<StepHikeCompact.Step step={2}> <StepHikeCompact.Details title="Add schema diff as a migration"> A new migration file is created for you.

  Alternately, you can copy the table definitions directly from the Table Editor.
</StepHikeCompact.Details>

<StepHikeCompact.Code>

create table "public"."cities" (
  "id" bigint primary key generated always as identity,
  "name" text,
  "population" bigint
);

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

<StepHikeCompact.Step step={3}> <StepHikeCompact.Details title="Test your migration"> Test your new migration file by resetting your local database. </StepHikeCompact.Details>

<StepHikeCompact.Code>

supabase db reset

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

The last step is deploying these changes to a live Supabase project.

Deploy your project

You've been developing your project locally, making changes to your tables via migrations. It's time to deploy your project to the Supabase Platform and start scaling up to millions of users!

Head over to Supabase and create a new project to deploy to.

<StepHikeCompact.Step step={1}> <StepHikeCompact.Details title="Log in to the Supabase CLI"> Login to the Supabase CLI using an auto-generated Personal Access Token. </StepHikeCompact.Details>

<StepHikeCompact.Code>

supabase login

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

<StepHikeCompact.Step step={2}> <StepHikeCompact.Details title="Link your project"> Link to your remote project by selecting from the on-screen prompt. </StepHikeCompact.Details>

<StepHikeCompact.Code>

supabase link

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

<StepHikeCompact.Step step={3}> <StepHikeCompact.Details title="Deploy database migrations"> Push your migrations to the remote database. </StepHikeCompact.Details>

<StepHikeCompact.Code>

supabase db push

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

<StepHikeCompact.Step step={4}> <StepHikeCompact.Details title="Deploy database seed data (optional)"> Push your migrations and seed the remote database. </StepHikeCompact.Details>

<StepHikeCompact.Code>

supabase db push --include-seed

</StepHikeCompact.Code>

</StepHikeCompact.Step> </StepHikeCompact>

Visiting your live project on Supabase, you'll see a new employees table, complete with the department column you added in the second migration above.