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Schema diff tutorial

Summary: Schema Diff tutorial for comparing a feature branch against a production branch in Neon using a side-by-side, GitHub-style diff. Available from the Console, the neon branches schema-diff CLI command, or the compare-schema REST API. Use this page when you need a concrete end-to-end example: create a database on production, branch it to a dev branch, alter the schema, then run Schema Diff to see exactly which tables, sequences, and constraints differ before merging or restoring.

Schema diff tutorial

Section titled “Schema diff tutorial”

Step-by-step guide showing you how to compare two development branches using Schema Diff

In this guide we will create an initial schema on a new database called people on our production branch. We'll then create a development branch called feature/address, following one possible convention for naming feature branches. After making schema changes on feature/address, we'll use the Schema Diff tool on the Branches page to get a side-by-side, GitHub-style visual comparison between the feature/address development branch and production.

Before you start

Section titled “Before you start”

To complete this tutorial, you'll need:

  • A Neon account. Sign up here.
  • To interact with your Neon database from the command line:

Create the Initial Schema

Section titled “Create the Initial Schema”

First, create a new database called people on the production branch and add some sample data to it.

Console

  1. Create the database.

    In the Neon Console, go to Postgres database > Databases → New Database. Make sure your production branch is selected, then create the new database called people.

  2. Add the schema.

    Go to Postgres database > SQL Editor, enter the following SQL statement and click Run to apply.

    SQL
    CREATE TABLE person (
    id SERIAL PRIMARY KEY,
    name TEXT NOT NULL,
    email TEXT UNIQUE NOT NULL
);

CLI

  1. Create the database.

    Use the following CLI command to create the people database.

    Bash
    neon databases create --name people

    Note:

    If you have multiple projects, include --project-id. Or set the project context so you don't have to specify project id in every command. Example:

    Bash
    neon set-context --project-id empty-glade-66712572

    You can find your project ID on the Settings page in the Neon Console.

  2. Copy your connection string:

    Bash
    neon connection-string --database-name people

  3. Connect to the people database with psql:

    Bash
    psql 'postgresql://neondb_owner:*********@ep-crimson-frost-a5i6p18z.us-east-2.aws.neon.tech/people?sslmode=require&channel_binding=require'

  4. Create the schema:

    SQL
    CREATE TABLE person (
    id SERIAL PRIMARY KEY,
    name TEXT NOT NULL,
    email TEXT UNIQUE NOT NULL
);

API

  1. Use the Create database API to create the people database, specifying the project_id, branch_id, database name, and database owner_name in the API call.

    Bash
    curl --request POST \
--url https://console.neon.tech/api/v2/projects/royal-band-06902338/branches/br-bitter-bird-a56n6lh4/databases \
--header 'accept: application/json' \
--header 'authorization: Bearer $NEON_API_KEY' \
--header 'content-type: application/json' \
--data '{
   "database": {
      "name": "people",
      "owner_name": "alex"
   }
}'

  2. Retrieve your database connection string using Get connection URI endpoint, specifying the required project_id, branch_id, database_name, and role_name parameters.

    Bash
    curl --request GET \
  --url 'https://console.neon.tech/api/v2/projects/royal-band-06902338/connection_uri?branch_id=br-bitter-bird-a56n6lh4&database_name=people&role_name=alex' \
  --header 'accept: application/json' \
  --header 'authorization: Bearer $NEON_API_KEY'

    The API call will return an connection string similar to this one:

    JSON
    {
  "uri": "postgresql://alex:*********@ep-green-surf-a5yaumj3-pooler.us-east-2.aws.neon.tech/people?sslmode=require&channel_binding=require"
}

  3. Connect to the people database with psql:

    Bash
    psql 'postgresql://alex:*********@ep-green-surf-a5yaumj3-pooler.us-east-2.aws.neon.tech/people?sslmode=require&channel_binding=require'

  4. Create the schema:

    SQL
    CREATE TABLE person (
    id SERIAL PRIMARY KEY,
    name TEXT NOT NULL,
    email TEXT UNIQUE NOT NULL
);

Create a development branch

Section titled “Create a development branch”

Create a new development branch off of production. This branch will be an exact, isolated copy of production.

For the purposes of this tutorial, name the branch feature/address, which could work as a good convention for creating isolated branches for working on specific features.

Console

  1. Create the development branch

    On the Branches page, click Create Branch, making sure of the following:

    • Select production as the parent branch.
    • Name the branch feature/address.

  2. Verify the schema on your new branch

    From the SQL Editor, use the meta-command \d person to inspect the schema of the person table. Make sure that the people database on the branch feature/address is selected.

    use metacommand to inspect schema

CLI

  1. Create the branch

    If you're still in psql, exit using \q.

    Using the Neon CLI, create the development branch. Include --project-id if you have multiple projects.

    Bash
    neon branches create --name feature/address --parent production

  2. Verify the schema

    To verify that this branch includes the initial schema created on production, connect to feature/address, then view the person table.

    1. Get the connection string for the people database on branch feature/address using the CLI.

      Bash
      neon connection-string feature/address --database-name people

      This gives you the connection string which you can then copy.

      Bash
      postgresql://neondb_owner:*********@ep-hidden-rain-a5pe72oi.us-east-2.aws.neon.tech/people?sslmode=require&channel_binding=require

    2. Connect to people using psql.

      Bash
      psql 'postgresql://neondb_owner:*********@ep-hidden-rain-a5pe72oi.us-east-2.aws.neon.tech/people?sslmode=require&channel_binding=require'

    3. View the schema for the person table we created earlier.

      Bash
      \d person

      Which shows you the schema:

      Bash
      Table "public.person"
Column |  Type   | Collation | Nullable |              Default
--------+---------+-----------+----------+------------------------------------
id     | integer |           | not null | nextval('person_id_seq'::regclass)
name   | text    |           | not null |
email  | text    |           | not null |
Indexes:
    "person_pkey" PRIMARY KEY, btree (id)
    "person_email_key" UNIQUE CONSTRAINT, btree (email)

      You can do the same thing for your production branch and get identical results.

API

Using the Create branch API, create a development branch named feature/address. You'll need to specify the project_id, parent_id, branch name, and add a read_write compute (you need a compute to connect to the branch).

Bash
curl --request POST \
--url https://console.neon.tech/api/v2/projects/royal-band-06902338/branches \
--header 'accept: application/json' \
--header 'authorization: Bearer $NEON_API_KEY' \
--header 'content-type: application/json' \
--data '{
   "branch": {
      "name": "feature/address",
      "parent_id": "br-bitter-bird-a56n6lh4"
   },
   "endpoints": [
      {
      "type": "read_write"
      }
   ]
}'

Update schema on a dev branch

Section titled “Update schema on a dev branch”

Let's introduce some differences between the two branches. Add a new table to store addresses on the feature/address branch.

Console

In the SQL Editor, make sure you select feature/address as the branch and people as the database.

Enter this SQL statement to create a new address table.

SQL
CREATE TABLE address (
    id SERIAL PRIMARY KEY,
    person_id INTEGER NOT NULL,
    street TEXT NOT NULL,
    city TEXT NOT NULL,
    state TEXT NOT NULL,
    zip_code TEXT NOT NULL,
    FOREIGN KEY (person_id) REFERENCES person(id)
);

CLI

  1. Connect to your feature/address branch

    By adding --psql to the CLI command, you can start the psql connection without having to enter the connection string directly:

    Bash
    neon connection-string feature/address --database-name people --psql

    Response:

    Bash
    INFO: Connecting to the database using psql...
psql (16.1, server 16.2)
SSL connection (protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384, compression: off)
Type "help" for help.

people=>

  2. Add a new address table

    SQL
    CREATE TABLE address (
    id SERIAL PRIMARY KEY,
    person_id INTEGER NOT NULL,
    street TEXT NOT NULL,
    city TEXT NOT NULL,
    state TEXT NOT NULL,
    zip_code TEXT NOT NULL,
    FOREIGN KEY (person_id) REFERENCES person(id)
);

API

  1. Retrieve the database connection string for the feature/address branch using Get connection URI endpoint:

    Bash
    curl --request GET \
  --url 'https://console.neon.tech/api/v2/projects/royal-band-06902338/connection_uri?branch_id=br-mute-dew-a5930esi&database_name=people&role_name=alex' \
  --header 'accept: application/json' \
  --header 'authorization: Bearer $NEON_API_KEY'

    The API call will return an connection string similar to this one:

    JSON
    {
  "uri": "postgresql://alex:*********@ep-hidden-sun-a5de9i5h-pooler.us-east-2.aws.neon.tech/people?sslmode=require&channel_binding=require"
}

  2. Connect to the people database on the feature/address branch with psql:

    Bash
    psql 'postgresql://alex:*********@ep-hidden-sun-a5de9i5h-pooler.us-east-2.aws.neon.tech/people?sslmode=require&channel_binding=require'

  3. Add a new address table.

    SQL
    CREATE TABLE address (
    id SERIAL PRIMARY KEY,
    person_id INTEGER NOT NULL,
    street TEXT NOT NULL,
    city TEXT NOT NULL,
    state TEXT NOT NULL,
    zip_code TEXT NOT NULL,
    FOREIGN KEY (person_id) REFERENCES person(id)
);

View the schema differences

Section titled “View the schema differences”

Now that you have some differences between your branches, you can view the schema differences.

Console

  1. Click on feature/address to open the detailed view, then click Schema diff.

    select branches for schema diff

  2. Make sure you select people as the database and then click Compare.

    schema diff results

You will see the schema differences between feature/address and its parent production, including the new address table that we added to the feature/address branch.

You can also launch Schema Diff from the Restore page, usually as part of verifying schemas before you restore a branch to its own or another branch's history. See Instant restore for more info.

CLI

Compare the schema of feature/address to its parent branch using the schema-diff command.

Bash
neon branches schema-diff production feature/address --database people

The result shows a comparison between the feature/address branch and its parent branch for the database people. The output indicates that the address table and its related sequences and constraints have been added in the feature/address branch but are not present in its parent branch production.

diff
--- Database: people (Branch: br-falling-dust-a5bakdqt)
+++ Database: people (Branch: br-morning-heart-a5ltt10i)
@@ -20,8 +20,46 @@

 SET default_table_access_method = heap;

 --
+-- Name: address; Type: TABLE; Schema: public; Owner: neondb_owner
+--
+
+CREATE TABLE public.address (
+    id integer NOT NULL,
+    person_id integer NOT NULL,
+    street text NOT NULL,
+    city text NOT NULL,
+    state text NOT NULL,
+    zip_code text NOT NULL
+);
+
+
+ALTER TABLE public.address OWNER TO neondb_owner;
+
+...

API

Compare the schema of the feature/address branch to its parent branch using the compare-schema API.

Bash
curl --request GET \
     --url 'https://console.neon.tech/api/v2/projects/royal-band-06902338/branches/br-mute-dew-a5930esi/compare_schema?base_branch_id=br-bitter-bird-a56n6lh4&db_name=neondb' \
     --header 'accept: application/json' \
     --header 'authorization: Bearer $NEON_API_KEY' | jq -r '.diff'
Parameter Description Required Example
<project_id> The ID of your Neon project. Yes royal-band-06902338
<branch_id> The ID of the target branch to compare. Yes br-mute-dew-a5930esi
<base_branch_id> The ID of the base branch for comparison (the parent branch in this case). Yes br-bitter-bird-a56n6lh4
<db_name> The name of the database in the target branch. Yes people
Authorization Bearer token for API access (your Neon API key) Yes $NEON_API_KEY

Note: The optional jq -r '.diff' command extracts the diff field from the JSON response and outputs it as plain text to make it easier to read. This command would not be necessary when using the endpoint programmatically.

The result shows a comparison between the feature/address branch and its parent branch for the database people. The output indicates that the address table and its related sequences and constraints have been added to the feature/address branch but are not present in its parent branch.

diff
--- a/people
+++ b/people
@@ -21,6 +21,44 @@
 SET default_table_access_method = heap;

 --
+-- Name: address; Type: TABLE; Schema: public; Owner: alex
+--
+
+CREATE TABLE public.address (
+    id integer NOT NULL,
+    person_id integer NOT NULL,
+    street text NOT NULL,
+    city text NOT NULL,
+    state text NOT NULL,
+    zip_code text NOT NULL
+);
+
+
+ALTER TABLE public.address OWNER TO alex;
+
+--
+-- Name: address_id_seq; Type: SEQUENCE; Schema: public; Owner: alex
+--
+
+CREATE SEQUENCE public.address_id_seq
+    AS integer
+    START WITH 1
+    INCREMENT BY 1
+    NO MINVALUE
+    NO MAXVALUE
+    CACHE 1;
+
+
+ALTER SEQUENCE public.address_id_seq OWNER TO alex;
+
+--
+-- Name: address_id_seq; Type: SEQUENCE OWNED BY; Schema: public; Owner: alex
+--
+
+ALTER SEQUENCE public.address_id_seq OWNED BY public.address.id;
+
+
+--
 -- Name: person; Type: TABLE; Schema: public; Owner: alex
 --

@@ -56,6 +94,13 @@


 --
+-- Name: address id; Type: DEFAULT; Schema: public; Owner: alex
+--
+
+ALTER TABLE ONLY public.address ALTER COLUMN id SET DEFAULT nextval('public.address_id_seq'::regclass);
+
+
+--
 -- Name: person id; Type: DEFAULT; Schema: public; Owner: alex
 --

@@ -63,6 +108,14 @@


 --
+-- Name: address address_pkey; Type: CONSTRAINT; Schema: public; Owner: alex
+--
+
+ALTER TABLE ONLY public.address
+    ADD CONSTRAINT address_pkey PRIMARY KEY (id);
+
+
+--
 -- Name: person person_email_key; Type: CONSTRAINT; Schema: public; Owner: alex
 --

@@ -79,6 +132,14 @@


 --
+-- Name: address address_person_id_fkey; Type: FK CONSTRAINT; Schema: public; Owner: alex
+--
+
+ALTER TABLE ONLY public.address
+    ADD CONSTRAINT address_person_id_fkey FOREIGN KEY (person_id) REFERENCES public.person(id);
+
+
+--
 -- Name: DEFAULT PRIVILEGES FOR SEQUENCES; Type: DEFAULT ACL; Schema: public; Owner: cloud_admin
 --

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