Heroku Postgres

Last updated 13 May 2020

Heroku Postgres is a managed SQL database service provided directly by Heroku. You can access a Heroku Postgres database from any language with a PostgreSQL driver, including all languages officially supported by Heroku.

In addition to a variety of management commands available via the Heroku CLI, Heroku Postgres provides a web dashboard, the ability to share queries with dataclips, and several other helpful features.

Provisioning Heroku Postgres

Before you provision Heroku Postgres, confirm that it isn’t already provisioned for your app (Heroku automatically provisions Postgres for apps that include certain libraries, such as the pg Ruby gem).

Use the heroku addons command to determine whether your app already has Heroku Postgres provisioned:

$ heroku addons
Add-on                                                      Plan       Price  State
──────────────────────────────────────────────────────────  ─────────  ─────  ───────
heroku-postgresql (postgresql-concave-52656)                hobby-dev  free   created

If heroku-postgresql doesn’t appear in your app’s list of add-ons, you can provision it with the following CLI command:

$ heroku addons:create heroku-postgresql:<PLAN_NAME>

For example, to provision a hobby-dev plan database:

$ heroku addons:create heroku-postgresql:hobby-dev
Creating heroku-postgresql:hobby-dev on ⬢ sushi... free
Database has been created and is available
 ! This database is empty. If upgrading, you can transfer
 ! data from another database with pg:copy
Created postgresql-concave-52656 as DATABASE_URL

You can specify the version of Postgres you want to provision by including the --version flag in your provisioning command:

$ heroku addons:create heroku-postgresql:<PLAN_NAME> --version=9.5

Learn more about PostgreSQL version support.

Depending on the plan you choose, your database can take up to 5 minutes to become available. You can track its status with the heroku pg:wait command, which blocks until your database is ready to use.

As part of the provisioning process, a DATABASE_URL config var is added to your app’s configuration. This contains the URL your app uses to access the database. If your app already has a Heroku Postgres database and you’ve just provisioned another one, this config var’s name instead has the format HEROKU_POSTGRESQL_<COLOR>_URL (for example, HEROKU_POSTGRESQL_YELLOW_URL).

You can confirm the names and values of your app’s config vars with the heroku config command.

At this point, an empty PostgreSQL database is provisioned. To populate it with data from an existing data source, see the import instructions or follow the language-specific instructions in this article to connect from your application.

Understanding Heroku Postgres plans

Heroku Postgres offers a variety of plans, spread across different tiers of service: hobby, standard, premium, and enterprise. For more information on what each plan provides, see Choosing the Right Heroku Postgres Plan.

Pricing information for Heroku Postgres plans is available on the Heroku Postgres add-on page.

If your app’s requirements eventually outgrow the resources provided by the initial plan you select, you can easily upgrade your database.

Designating a primary database

Heroku apps use the DATABASE_URL config var to designate the URL of an app’s primary database. If your app only has one database, its URL is automatically assigned to this config var.

For apps with multiple databases, you can set the primary database with the heroku pg:promote command:

$ heroku pg:promote HEROKU_POSTGRESQL_YELLOW
Promoting HEROKU_POSTGRESQL_YELLOW_URL to DATABASE_URL... done

You can specify the “color” identifier or add-on name associated with the database you want to promote.

Sharing Heroku Postgres between applications

You can share a single Heroku Postgres database between multiple apps with the heroku addons:attach command:

$ heroku addons:attach my-originating-app::DATABASE --app sushi
Attaching postgresql-addon-name to sushi... done
Setting HEROKU_POSTGRESQL_BRONZE vars and restarting sushi... done, v11

The attached database’s URL is assigned to a config var with the name format HEROKU_POSTGRESQL_[COLOR]_URL. In the above example, the config var’s name is HEROKU_POSTGRESQL_BRONZE_URL.

A shared database is not necessarily the primary database for any given app that it’s shared with. You promote a shared database with the same command that you use for any other database.

You can stop sharing your Heroku Postgres instance with another app with the heroku addons:detach command:

$ heroku addons:detach HEROKU_POSTGRESQL_BRONZE --app sushi
Detaching HEROKU_POSTGRESQL_BRONZE to postgresql-addon-name from sushi... done
Unsetting HEROKU_POSTGRESQL_BRONZE config vars and restarting sushi... done, v11

Version support

The PostgreSQL project releases new major versions on a yearly basis. Each major version is supported by Heroku Postgres shortly after its release.

Heroku Postgres supports at least 3 major versions at a given time. Currently supported versions are:

• 12 (default)
• 11
• 10
• 9.6
• 9.5
• 9.4 - deprecating

Users are required to upgrade roughly once every three years. However, you can upgrade your database at any point to gain the benefits of the latest version.

Migration of deprecated databases

The PostgreSQL project stops supporting a major version five years after its initial release. Heroku Postgres deprecates these versions to ensure no databases run on an unsupported major version of PostgreSQL.

• One year before a version’s end of life (EOL), Heroku prevents provisioning a new database on the deprecated version (forks and followers of existing databases are still allowed).
• Six (6) months before EOL, customers receive a notification that they must upgrade and directions on how to do so on your own schedule.
• Three (3) months before EOL, we schedule forced upgrade maintenances for any remaining databases.

Heroku highly recommends that you perform the version upgrade or update prior to support ending, so that you can test compatibility, plan for unforeseen issues, and migrate your database on your own schedule.

Legacy Infrastructure

Heroku also occasionally deprecates old versions of its infrastructure. This typically occurs for one of the following reasons:

• The operating system running beneath the database will soon no longer receive security updates.
• Support for the operating system is no longer practical due to its age (if required packages and patches are no longer available or difficult to support).
• The server instances are significantly different from Heroku’s current infrastructure and are impractical to support.

To see if your database is running on legacy infrastructure, use pg:info:

$ heroku pg:info

=== HEROKU_POSTGRESQL_MAROON_URL (DATABASE_URL)
Plan:           Ronin
Status:         Available
Data Size:      26.1 MB
Tables:         5
PG Version:     9.5.3
Connections:    2
Fork/Follow:    Available
Rollback:       Unsupported
Created:        2012-05-02 21:54 UTC
Maintenance:    not required (Mondays 23:00 to Tuesdays 03:00 UTC)
Infrastructure: Legacy

Performance analytics

Performance analytics is the visibility suite for Heroku Postgres. It enables you to monitor the performance of your database and diagnose potential problems. It consists of several components:

Expensive queries

The leading cause of poor database performance is unoptimized queries. The list of your most expensive queries, available through data.heroku.com, helps to identify and understand the queries that take the most time in your database. Full documentation is available here.

Logging

If your application/framework emits logs on database access, you can retrieve them through Heroku’s log-stream:

$ heroku logs -t

To see logs from the database service itself, use heroku logs with the -p postgres option to see only the logs from Postgres:

$ heroku logs -p postgres -t

pg:diagnose

pg:diagnose performs a number of useful health and diagnostic checks that help analyze and optimize database performance. It produces a report that you can share with teammates or Heroku Support.

$ heroku pg:diagnose --app sushi
Report 1234abc… for sushi::HEROKU_POSTGRESQL_MAROON_URL
available for one month after creation on 2014-07-03 21:29:40.868968+00

GREEN: Connection Count
GREEN: Long Queries
GREEN: Long Transactions
GREEN: Idle in Transaction
GREEN: Indexes
GREEN: Bloat
GREEN: Hit Rate
GREEN: Blocking Queries
GREEN: Sequences
GREEN: Table Transaction ID Wraparound
GREEN: Database Transaction ID Wraparound
GREEN: Schema Count
GREEN: Load

Check: Connection Count

Each Postgres connection requires memory, and database plans have a limit on the number of connections they can accept. If you are using too many connections, consider using a connection pooler such as PgBouncer or migrating to a larger plan with more RAM.

Checks: Long Running Queries, Long Transactions, Idle in Transaction

Long-running queries and transactions can cause problems with bloat that prevent auto vacuuming and cause followers to lag behind. They also create locks on your data, which can prevent other transactions from running. Consider killing long-running queries with pg:kill.

Backends that are idle in transaction are backends that are waiting on the client to finish the transaction, either through COMMIT; or ROLLBACK. Clients that have improperly disconnected may leave backends in this state, and they should be terminated with pg:kill --force if left open.

Check: Indexes

The Indexes check includes three classes of indexes.

Never Used Indexes have not been used (since the last manual database statistics refresh). These indexes are typically safe to drop, unless they are in use on a follower.

Low Scans, High Writes indexes are used, but infrequently relative to their write volume. Indexes are updated on every write, so are especially costly on a high write table. Consider the cost of slower writes against the performance improvements that these indexes provide.

Seldom used Large Indexes are not used often and take up significant space both on disk and in cache (RAM). These indexes may still be important to your application, for example, if they are used by periodic jobs or infrequent traffic patterns.

Index usage is only tracked on the database receiving the query. If you use followers for reads, this check will not account for usage made against the follower and is likely inaccurate.

Check: Bloat

Because Postgres uses MVCC old versions of updated or deleted rows are simply made invisible rather than modified in place. Under normal operation an auto vacuum process goes through and asynchronously cleans these up. However sometimes it cannot work fast enough or otherwise cannot prevent some tables from becoming bloated. High bloat can slow down queries, waste space, and even increase load as the database spends more time looking through dead rows.

You can manually vacuum a table with the VACUUM (VERBOSE, ANALYZE); command in psql. If this occurs frequently you may want to make autovacuum more aggressive.

It’s important to note that the bloat estimaton calculation may not be accurate for tables that use columns that do not have column statistics, such as json columns. This is especially pronounced on Postgres 9.4 and below.

Check: Hit Rate

This checks the overall index hit rate, the overall cache hit rate, and the individual index hit rate per table. Databases with lower cache hit rates perform significantly worse as they have to hit disk instead of reading from memory. Consider migrating to a larger plan for low cache hit rates, and adding appropriate indexes for low index hit rates.

The overall cache hit rate is calculated as a ratio of table data blocks fetched from the Postgres buffer cache against the sum of cached blocks and un-cached blocks read from disk. On larger plans, the cache hit ratio may be lower but performance remains constant, as the remainder of the data is cached in memory by the OS rather than Postgres.

The overall index hit rate is calculated as a ratio of index blocks fetched from the Postgres buffer cache against the sum of cached indexed blocks and un-cached index blocks read from disk. On larger plans, the index hit ratio may be lower, but performance remains constant, as the remainder of the index data is cached in memory by the OS rather than Postgres.

The individual index hit rate per table is calculated as a ratio of index scans against a table versus the sum of sequential scans and index scans against the table.

Check: Blocking Queries

Some queries can take locks that block other queries from running. Normally these locks are acquired and released very quickly and do not cause any issues. In pathological situations however some queries can take locks that cause significant problems if held too long. You may want to consider killing the query with pg:kill.

Check: Sequences

This looks at 32bit integer (aka int4) columns that have associated sequences, and reports on those that are getting close to the maximum value for 32bit ints. You should migrate these columns to 64bit bigint (aka int8) columns to avoid overflow. An example of such a migration is alter table products alter column id type bigint;. Changing the column type can be an expensive operation, and sufficient planning should be made for this on large tables. There is no reason to prefer integer columns over bigint columns (aside from composite indexes) on Heroku Postgres due to alignemnt considerations on 64bit systems.

Check: Table Transaction ID Wraparound, Database Transaction ID Wraparound

These checks determine how close individual tables are, or a database is, to transaction ID wraparound. This is a very rare scenario in which due to autovacuum operations being unable to keep up on very frequently updated tables, these tables are in danger of the transaction ID for that table, or database, wrapping around and resulting in data loss. To prevent this, Postgres will prevent new writes cluster wide until this is resolved, impacting availability. These checks return the table and database names if over 50% of the transaction ID space has been used.

Check: Schema Count

This check counts the number of schema are present in the database, returning a yellow warning for over 19 schema, and a red warning over 50 schema. Postgres performance and the ability to take successful logical backups can be affected significantly with very large numbers of schema, and we recommend to maintain no more than 50 schema.

Check: Load

There are many, many reasons that load can be high on a database: bloat, CPU intensive queries, index building, and simply too much activity on the database. Review your access patterns, and consider migrating to a larger plan which would have a more powerful processor.

Local setup

• Mac setup
• Windows setup
• Linux setup

Heroku recommends running Postgres locally to ensure parity between environments. There are several pre-packaged installers for installing PostgreSQL in your local environment.

Once Postgres is installed and you can connect, you’ll need to export the DATABASE_URL environment variable for your app to connect to it when running locally:

-- for Mac and Linux
$ export DATABASE_URL=postgres://$(whoami)
-- for Windows
$ set DATABASE_URL=postgres://$(whoami)

This tells Postgres to connect locally to the database matching your user account name (which is set up as part of installation).

Set up Postgres on Mac

1. Install Postgres.app and follow setup instructions.
2. Install the postgres CLI tools.
3. Open up a new terminal window to ensure your changes have been saved.
4. Verify that it worked correctly. The OS X version of psql should point to the path containing the Postgres.app directory.

If you are using version 9.5, the output looks similar to this:

$ which psql
/Applications/Postgres.app/Contents/Versions/latest/bin/psql

This command should work correctly:

$ createdb
$  psql -h localhost
psql (9.5.2)
Type "help" for help.
=# \q

Also verify that the app is set to automatically start at login.

PostgreSQL ships with several useful binaries, such as pg_dump and pg_restore, that you will likely want to use. Add the /bin directory that ships with Postgres.app to your PATH (preferably in .profile, .bashrc, .zshrc, or the like to make sure this is set for every terminal session):

PATH="/Applications/Postgres.app/Contents/Versions/latest/bin:$PATH"

Set up Postgres on Windows

Install Postgres on Windows by using the Windows installer.

Set up Postgres on Linux

Install Postgres via your package manager. The actual package manager command you use will depend on your distribution. The following will work on Ubuntu, Debian, and other Debian-derived distributions:

$ sudo apt-get install postgresql

If you do not have a package manager on your distribution or the Postgres package is not available, install Postgres on Linux using one of the Generic installers.

The psql client will typically be installed in /usr/bin:

$ which psql
/usr/bin/psql

and the command should work correctly:

$ psql
psql (9.3.5)
Type "help" for help.
maciek# \q

Using the CLI

Heroku Postgres is integrated directly into the Heroku CLI and offers many helpful commands that simplify common database tasks.

pg:info

To see all PostgreSQL databases provisioned by your application and the identifying characteristics of each (such as database size, status, number of tables, and PG version), use the heroku pg:info command:

$ heroku pg:info
=== HEROKU_POSTGRESQL_RED
Plan         Standard 0
Status       available
Data Size    82.8 GB
Tables       13
PG Version   9.5.3
Created      2012-02-15 09:58 PDT
=== HEROKU_POSTGRESQL_GRAY
Plan         Standard 2
Status       available
Data Size    82.8 GB
…

To continuously monitor the status of your database, pass pg:info through the unix watch command:

$ watch heroku pg:info

pg:psql

To establish a psql session with your remote database, use heroku pg:psql.

$ heroku pg:psql
Connecting to HEROKU_POSTGRESQL_RED... done
psql (9.5.3, server 9.5.3)
SSL connection (cipher: DHE-RSA-AES256-SHA, bits: 256)
Type "help" for help.

rd2lk8ev3jt5j50=> SELECT * FROM users;

If you have more than one database, specify the database to connect to (just the color works as a shorthand) as the first argument to the command (the database located at DATABASE_URL is used by default).

$ heroku pg:psql gray
Connecting to HEROKU_POSTGRESQL_GRAY... done
...

pg:push and pg:pull

pg:pull

pg:pull can be used to pull remote data from a Heroku Postgres database to a database on your local machine. The command looks like this:

$ heroku pg:pull HEROKU_POSTGRESQL_MAGENTA mylocaldb --app sushi

This command creates a new local database named mylocaldb and then pulls data from the database at DATABASE_URL from the app sushi. To prevent accidental data overwrites and loss, the local database must not already exist. You will be prompted to drop an already existing local database before proceeding.

If providing a Postgres user or password for your local DB is necessary, use the appropriate environment variables like so:

$ PGUSER=postgres PGPASSWORD=password heroku pg:pull HEROKU_POSTGRESQL_MAGENTA mylocaldb --app sushi

pg:push

pg:push pushes data from a local database into a remote Heroku Postgres database. The command looks like this:

$ heroku pg:push mylocaldb HEROKU_POSTGRESQL_MAGENTA --app sushi

This command takes the local database mylocaldb and pushes it to the database at DATABASE_URL on the app sushi. To prevent accidental data overwrites and loss, the remote database must be empty. You will be prompted to pg:reset a remote database that is not empty.

Usage of the PGUSER and PGPASSWORD for your local database is also supported for pg:push, just like for the pg:pull command.

Troubleshooting

These commands rely on the pg_dump and pg_restore binaries that are included in a Postgres installation. It is somewhat common, however, for the wrong binaries to be loaded in $PATH. Errors such as

!    createdb: could not connect to database postgres: could not connect to server: No such file or directory
!      Is the server running locally and accepting
!      connections on Unix domain socket "/var/pgsql_socket/.s.PGSQL.5432"?
!
!    Unable to create new local database. Ensure your local Postgres is working and try again.

and

pg_dump: server version: 9.5.3; pg_dump version: 9.5.3
pg_dump: aborting because of server version mismatch
pg_dump: *** aborted because of error
pg_restore: [archiver] input file is too short (read 0, expected 5)

are both often a result of this incorrect $PATH problem. This problem is especially common with Postgres.app users, as the post-install step of adding /Applications/Postgres.app/Contents/MacOS/bin to $PATH is easy to forget.

pg:ps, pg:kill, pg:killall

These commands give you view and control over currently running queries.

The pg:ps command queries the pg_stat_activity view in Postgres to give a concise view into currently running queries.

$ heroku pg:ps
 procpid |         source            |   running_for   | waiting |         query
---------+---------------------------+-----------------+---------+-----------------------
   31776 | psql                      | 00:19:08.017088 | f       | <IDLE> in transaction
   31912 | psql                      | 00:18:56.12178  | t       | select * from hello;
   32670 | Heroku Postgres Data Clip | 00:00:25.625609 | f       | BEGIN READ ONLY; select 'hi'
(3 rows)

The procpid column can then be used to cancel or terminate those queries with pg:kill. Without any arguments pg_cancel_backend is called on the query which will attempt to cancel the query. In some situations that can fail, in which case the --force option can be used to issue pg_terminate_backend which drops the entire connection for that query.

$ heroku pg:kill 31912
 pg_cancel_backend
-------------------
 t
(1 row)

$ heroku pg:kill --force 32670
 pg_terminate_backend
----------------------
 t
(1 row)

pg:killall is similar to pg:kill except it will cancel or terminate every query on your database.

pg:promote

In setups where more than one database is provisioned (common use-cases include a leader/follower high-availability setup or as part of the database upgrade process) it is often necessary to promote an auxiliary database to the primary role. This is accomplished with the heroku pg:promote command.

$ heroku pg:promote HEROKU_POSTGRESQL_GRAY_URL
Promoting HEROKU_POSTGRESQL_GRAY_URL to DATABASE_URL... done

pg:promote works by setting the value of the DATABASE_URL config var (which your application uses to connect to the primary database) to the newly promoted database’s URL and restarting your app. The old primary database location is still accessible via its HEROKU_POSTGRESQL_COLOR_URL setting.

pg:credentials

Heroku Postgres provides convenient access to the credentials and location of your database should you want to use a GUI to access your instance.

$ heroku pg:credentials:url DATABASE
Connection info string:
   "dbname=dee932clc3mg8h host=ec2-123-73-145-214.compute-1.amazonaws.com port=6212 user=user3121 password=98kd8a9 sslmode=require"

It is a good security practice to rotate the credentials for important services on a regular basis. On Heroku Postgres this can be done with heroku pg:credentials:rotate.

$ heroku pg:credentials:rotate HEROKU_POSTGRESQL_GRAY_URL

When you issue this command, new credentials are created for your database and the related config vars on your Heroku application are updated. However, on Standard, Premium, and Enterprise tier databases the old credentials are not removed immediately. All of the open connections remain open until the currently running tasks complete, then those credentials are updated. This is to make sure that any background jobs or other workers running on your production environment aren’t abruptly terminated, which could potentially leave the system in an inconsistent state.

pg:reset

The PostgreSQL user your database is assigned doesn’t have permission to create or drop databases. To drop and recreate your database use pg:reset.

$ heroku pg:reset DATABASE

Heroku Postgres & SSL

Most clients will connect over SSL by default, but on occasion it is necessary to set the sslmode=require parameter on a Postgres connection. Please add this parameter in code rather than editing the config var directly. Please check you are enforcing use of SSL especially if you are using Java or Node.js clients.

Connecting in Java

There are a variety of ways to create a connection to a Heroku Postgres database, depending on the Java framework in use. In most cases, the environment variable JDBC_DATABASE_URL can be used directly as described in the article Connecting to Relational Databases on Heroku with Java. Here is an example:

private static Connection getConnection() throws URISyntaxException, SQLException {
    String dbUrl = System.getenv("JDBC_DATABASE_URL");
    return DriverManager.getConnection(dbUrl);
}

When it is not possible to use the JDBC URL (usually because custom buildpack is being used), you must use the DATABASE_URL environment URL to determine connection information. Some examples are provided below.

By default, Heroku will attempt to enable SSL for the PostgreSQL JDBC driver by setting the property sslmode=require globally. However, if you are building the JDBC URL yourself (such as by parsing the DATABASE_URL) then we recommend explicitly adding this parameter.

It is also important that you use a version of the Postgres JDBC driver verion 9.2 or greater. For example, in Maven add this to your pom.xml:

<dependency>
  <groupId>org.postgresql</groupId>
  <artifactId>postgresql</artifactId>
  <version>42.2.1</version>
</dependency>

JDBC

Create a JDBC connection to Heroku Postgres by parsing the DATABASE_URL environment variable.

private static Connection getConnection() throws URISyntaxException, SQLException {
    URI dbUri = new URI(System.getenv("DATABASE_URL"));

    String username = dbUri.getUserInfo().split(":")[0];
    String password = dbUri.getUserInfo().split(":")[1];
    String dbUrl = "jdbc:postgresql://" + dbUri.getHost() + ':' + dbUri.getPort() + dbUri.getPath() + "?sslmode=require";

    return DriverManager.getConnection(dbUrl, username, password);
}

Spring/XML

This snippet of Spring XML configuration will setup a BasicDataSource from the DATABASE_URL and can then be used with Hibernate, JPA, etc:

<bean class="java.net.URI" id="dbUrl">
    <constructor-arg value="#{systemEnvironment['DATABASE_URL']}"/>
</bean>

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
    <property name="url" value="#{ 'jdbc:postgresql://' + @dbUrl.getHost() + ':' + @dbUrl.getPort() + @dbUrl.getPath() + '?sslmode=require' }"/>
    <property name="username" value="#{ @dbUrl.getUserInfo().split(':')[0] }"/>
    <property name="password" value="#{ @dbUrl.getUserInfo().split(':')[1] }"/>
</bean>

Spring/Java

Alternatively you can use Java for configuration of the BasicDataSource in Spring:

@Configuration
public class MainConfig {

    @Bean
    public BasicDataSource dataSource() throws URISyntaxException {
        URI dbUri = new URI(System.getenv("DATABASE_URL"));

        String username = dbUri.getUserInfo().split(":")[0];
        String password = dbUri.getUserInfo().split(":")[1];
        String dbUrl = "jdbc:postgresql://" + dbUri.getHost() + ':' + dbUri.getPort() + dbUri.getPath() + "?sslmode=require";

        BasicDataSource basicDataSource = new BasicDataSource();
        basicDataSource.setUrl(dbUrl);
        basicDataSource.setUsername(username);
        basicDataSource.setPassword(password);

        return basicDataSource;
    }
}

The DATABASE_URL for the Heroku Postgres add-on follows this naming convention:

postgres://<username>:<password>@<host>/<dbname>

However the Postgres JDBC driver uses the following convention:

jdbc:postgresql://<host>:<port>/<dbname>?sslmode=require&user=<username>&password=<password>

Notice the additional ql at the end of jdbc:postgresql? Due to this difference you will need to hardcode the scheme to jdbc:postgresql in your Java class or your Spring XML configuration.

Remote connections

You can connect to your Heroku Postgres database remotely for maintenance and debugging purposes. However, doing so requires that you use an SSL connection. Your JDBC connection URL will need to include the following URL parameter:

sslmode=require

If you leave off sslmode=require you will get a connection error when attempting to connect to production-tier databases.

Note: it is important to add this parameter in code rather than editing the config var directly. Various automated events such as failover can change the config var, and edits there would be lost.

Click here for more information see the Dev Center article on Connecting to Relational Databases on Heroku with Java.

Connecting in Ruby

To use PostgreSQL as your database in Ruby applications you will need to include the pg gem in your Gemfile.

gem 'pg'

Run bundle install to download and resolve all dependencies.

If you are using the pg gem to connect to your Postgres database from a Heroku dyno, and have not specified an sslmode in your configuration or code, the gem will default to sslmode: prefer: this means that your connections will work if SSL use is enforced on your Postgres database.

Connecting in Rails

When Rails applications are deployed to Heroku a database.yml file is automatically generated for your application. That configures ActiveRecord to use a PostgreSQL connection and to connect to the database located at DATABASE_URL. This behavior is only needed up to Rails 4.1. Any later version contains direct support for specifying a connection URL and configuration in the database.yml so we do not have to overwrite it.

To use PostgreSQL locally with a Rails app your database.yml should contain the following configuration:

development:
  adapter: postgresql
  host: localhost
  username: user
  database: app-dev

Connecting in JRuby

To use PostgreSQL as your database in JRuby applications you will need to include the activerecord-jdbcpostgresql-adapter gem in your Gemfile.

gem 'activerecord-jdbcpostgresql-adapter'

Run bundle install to download and resolve all dependencies.

If using Rails, follow the instructions for Connecting with Rails.

Connecting in Python

To use PostgreSQL as your database in Python applications you will need to use the psycopg2 package.

$ pip install psycopg2-binary

And use this package to connect to DATABASE_URL in your code.

import os
import psycopg2

DATABASE_URL = os.environ['DATABASE_URL']

conn = psycopg2.connect(DATABASE_URL, sslmode='require')

Connecting with Django

Install the dj-database-url package using pip.

$ pip install dj-database-url

Then add the following to the bottom of settings.py:

import dj_database_url
DATABASES['default'] = dj_database_url.config(conn_max_age=600, ssl_require=True)

This will parse the values of the DATABASE_URL environment variable and convert them to something Django can understand.

Connecting in Go

Go apps can connect to Heroku-Postgres by providing the pq Postgres database driver to their query interface of choice (such as the standard database/sql). Your app will use the query interface, rather than using the driver directly.

Standard usage (database/sql)

$ cd <app>
$ dep ensure -add github.com/lib/pq

import (
  "database/sql"
  _ "github.com/lib/pq"
)
...
func main() {
  db, err := sql.Open("postgres", os.Getenv("DATABASE_URL"))
  if err != nil {
    log.Fatal(err)
  }
  ...
}

Beyond the standard lib

For lower-level access to Postgres, you can use pgx.

For time-saving extensions to database/sql, you can use sqlx.

Connecting in PHP

General considerations

If a framework or library cannot natively handle database URLs, and instead requires separate arguments for user, pass, host, port, database name and so on, then the parse_url() function can be used to parse the DATABASE_URL environment variable and establish a connection using the extracted details.

$db = parse_url(getenv("DATABASE_URL"));
$db["path"] = ltrim($db["path"], "/");

The resulting associative array will contain the information from the URL, as documented, with the database name available through the “path” key.

Connecting with the pgsql extension

The pgsql extension passes connection strings directly to the underlying libpq library, which supports URL-style connection strings, so the DATABASE_URL environment variable can be used directly:

$conn = pg_connect(getenv("DATABASE_URL"));

Connecting with PDO

A DSN needs to be constructed to connect using PDO:

$db = parse_url(getenv("DATABASE_URL"));

$pdo = new PDO("pgsql:" . sprintf(
    "host=%s;port=%s;user=%s;password=%s;dbname=%s",
    $db["host"],
    $db["port"],
    $db["user"],
    $db["pass"],
    ltrim($db["path"], "/")
));

Connecting with Laravel

The config/database.php file returns an array of database connection info to the framework; it can simply be amended to call parse_url() on the DATABASE_URL environment variable first, and return the extracted data:

$DATABASE_URL = parse_url(getenv("DATABASE_URL"));

return [

    // …

    'connections' => [

        // …

        'pgsql' => [
            'driver' => 'pgsql',
            'host' => $DATABASE_URL["host"],
            'port' => $DATABASE_URL["port"],
            'database' => ltrim($DATABASE_URL["path"], "/"),
            'username' => $DATABASE_URL["user"],
            'password' => $DATABASE_URL["pass"],
            'charset' => 'utf8',
            'prefix' => '',
            'schema' => 'public',
            'sslmode' => 'require',
        ],

        // …

    ],

    // …

];

Connecting with Symfony 3

The DATABASE_URL environment variable can be referenced in config.yml; Symfony’s DoctrineBundle will then automatically parse the URL’s contents.

Connecting with Symfony 4

Symfony 4 will automatically pick up the DATABASE_URL environment variable without further configuration.

Connecting in Node.js

Install the pg NPM module as a dependency:

$ npm install pg

Then, connect to process.env.DATABASE_URL:

const { Client } = require('pg');

const client = new Client({
  connectionString: process.env.DATABASE_URL,
  ssl: {
    rejectUnauthorized: false
  }
});

client.connect();

client.query('SELECT table_schema,table_name FROM information_schema.tables;', (err, res) => {
  if (err) throw err;
  for (let row of res.rows) {
    console.log(JSON.stringify(row));
  }
  client.end();
});

Connection permissions

Heroku Postgres users are granted all non-superuser permissions on their database. These include SELECT, INSERT, UPDATE, DELETE, TRUNCATE, REFERENCES, TRIGGER, CREATE, CONNECT, TEMPORARY, EXECUTE, and USAGE and limited ALTER and GRANT permissions.

Heroku runs the SQL below to create a user and database for you.

CREATE ROLE user_name;
ALTER ROLE user_name WITH LOGIN PASSWORD 'password' NOSUPERUSER NOCREATEDB NOCREATEROLE;
CREATE DATABASE database_name OWNER user_name;
REVOKE ALL ON DATABASE database_name FROM PUBLIC;
GRANT CONNECT ON DATABASE database_name TO user_name;
GRANT ALL ON DATABASE database_name TO user_name;

Multiple schemas

Heroku Postgres supports multiple schemas and does not place any limits on the number of schemas you can create.

External connections (ingress)

In addition to being available to the Heroku runtime, Heroku Postgres databases can be accessed directly by clients running on your local computer or elsewhere.

You can retrieve the PG connection string in one of two ways. heroku pg:credentials is discussed above:

$ heroku pg:credentials DATABASE
Connection info string:
   "dbname=dee932clc3mg8h host=ec2-123-73-145-214.compute-1.amazonaws.com port=6212 user=user3121 password=98kd8a9 sslmode=require"

Also, the connection string is exposed as a config var for your app:

$ heroku config | grep HEROKU_POSTGRESQL
HEROKU_POSTGRESQL_YELLOW_URL: postgres://user3123:passkja83kd8@ec2-117-21-174-214.compute-1.amazonaws.com:6212/db982398

Migrating between plans

See this detailed guide on updating and migrating between database plans.

Data Residency

When a database gets provisioned, the data associated with that database is stored within the region in which it’s created. However, a number of services that are ancillary to Heroku Postgres as well as the systems that manage the fleet of databases may not be located within the same region as the provisioned databases. Here are some

• Postgres Continuous Protection for disaster recovery stores the base backup and write-ahead logs in the same region that the database is located.
• Application logs are routed to Logplex, which is hosted in the US. In addition to logs from your application, this includes System logs and Heroku Postgres logs from any database attached to your application.
• Logging of Heroku Postgres queries and errors can be blocked by using the --block-logs flag when creating the database with heroku addons:create heroku-postgres:....
• PG Backup snapshots are stored in the US.
• Dataclips are stored in the US.

Blocking Logs

At add-on creation time, a flag can be passed to prevent logging of queries that get run against the database. If this option is turned on, it cannot be turned off after the database has been provisioned. If you need to turn it off after it has been turned on, a migration to a new database will be required.

$ heroku addons:create heroku-postgresql:standard-0 -a sushi --block-logs

Removing the add-on

In order to destroy your Heroku Postgres database you will need to remove the add-on.

$ heroku addons:destroy heroku-postgresql:hobby-dev

If you have two databases of the same type you will need to remove the add-on using its config var name. For example, to remove the HEROKU_POSTGRESQL_GRAY_URL, you would run:

heroku addons:destroy HEROKU_POSTGRESQL_GRAY

If the removed database was the same one used in DATABASE_URL, that DATABASE_URL config var will also be unset on the app.

Support

All Heroku Postgres support and runtime issues should be submitted via one of the Heroku Support channels.