Darian Vance

Posted on Jan 22 • Originally published at wp.me

Solved: Migrating Heroku Postgres Data to Render PostgreSQL

#devops #programming #tutorial #cloud

🚀 Executive Summary

TL;DR: This guide provides a robust, step-by-step methodology for migrating Heroku Postgres data to Render PostgreSQL, prompted by Heroku’s evolving pricing. It leverages pg\_dump and pg\_restore utilities to ensure a seamless, efficient transfer with minimal disruption and data integrity.

🎯 Key Takeaways

Enable Heroku application maintenance mode (heroku maintenance:on) before export to ensure data consistency and prevent new writes.
Use pg\_dump -Fc –no-acl –no-owner to create a flexible, compressed backup from Heroku Postgres, excluding access privileges and object ownership to prevent conflicts.
Provision a new PostgreSQL instance on Render and retrieve its External Database URL for the import process.
Employ pg\_restore –verbose –clean –no-acl –no-owner to import the dump file into Render PostgreSQL, dropping existing objects and again preventing permission/ownership conflicts.
Thoroughly verify data integrity on the Render database using psql and update your application’s DATABASE\_URL environment variable to point to the new Render instance.

Migrating Heroku Postgres Data to Render PostgreSQL

As a Senior DevOps Engineer and Technical Writer at TechResolve, I understand the critical need for efficient, cost-effective infrastructure. In today’s dynamic cloud landscape, platforms evolve, and so do their pricing models. Heroku, a beloved PaaS for many, has recently undergone significant changes, prompting many organizations to evaluate alternative solutions. Among the contenders, Render stands out with its developer-friendly environment and competitive pricing.

Migrating a critical component like your production database can feel like a daunting task, fraught with potential downtime and data integrity concerns. Manual processes are not only tedious but also prone to human error, consuming valuable engineering time that could be better spent innovating. This comprehensive guide from TechResolve aims to demystify the process, providing a robust, step-by-step methodology to seamlessly migrate your Heroku Postgres data to a Render PostgreSQL instance.

By following this tutorial, you will learn how to safely and efficiently transfer your valuable database, ensuring minimal disruption and setting the stage for a smoother, potentially more cost-optimized cloud infrastructure on Render. Let’s dive in and take control of your data migration!

Prerequisites

Before we begin the migration process, ensure you have the following tools and accounts ready:

Heroku Account and CLI: You must have an active Heroku account and the Heroku CLI installed and logged in. Ensure you have access to the Heroku application whose Postgres database you wish to migrate.
Render Account: An active Render account is required. You will need to provision a PostgreSQL database instance on Render.
PostgreSQL Client Utilities:
- psql: The PostgreSQL interactive terminal.
- pg_dump: A utility for backing up a PostgreSQL database.
- pg_restore: A utility for restoring a PostgreSQL database archive created by pg_dump.

These are typically included with a standard PostgreSQL installation. If you don’t have them, you can install PostgreSQL locally or use a containerized environment.

Sufficient Local Storage: Ensure your local machine has enough disk space to temporarily store a backup of your Heroku Postgres database.
Basic Database Knowledge: Familiarity with SQL and PostgreSQL concepts will be beneficial.

Step-by-Step Guide: Migrating Your Database

Step 1: Prepare Your Heroku Postgres Database for Export

To ensure data consistency and prevent potential issues during the dump process, it’s highly recommended to put your Heroku application into maintenance mode. This will stop new writes to the database, creating a quiescent state for a clean export. While not strictly mandatory for pg_dump, it’s a best practice for production migrations.

First, enable maintenance mode for your Heroku application:

heroku maintenance:on -a your-heroku-app-name

Replace your-heroku-app-name with the actual name of your Heroku application.

Next, retrieve the connection string for your Heroku Postgres database. This URL contains all the necessary credentials (host, port, user, password, database name) for pg_dump to connect.

heroku config:get DATABASE_URL -a your-heroku-app-name

You will get an output similar to postgres://user:password@host:port/database. Keep this URL handy.

Step 2: Export Data from Heroku Postgres

Now, we will use pg_dump to create a backup of your Heroku Postgres database. We’ll use the custom format (-Fc) which is highly flexible and recommended for migrations as it allows for selective restoration and is more efficient than plain SQL dumps for large databases.

Execute the following command, replacing HEROKU_DATABASE_URL with the actual URL you obtained in Step 1, and your_heroku_dump.dump with your desired filename for the backup:

pg_dump -Fc --no-acl --no-owner -d "HEROKU_DATABASE_URL" > your_heroku_dump.dump

Let’s break down these options:

-Fc: Specifies the custom format output file. This format is compressed and allows for greater flexibility during restore.
--no-acl: Prevents dumping access privileges (GRANT/REVOKE commands). This is crucial because user roles and permissions on Heroku are specific and often won’t directly map to your new Render PostgreSQL instance.
--no-owner: Prevents dumping commands to set object ownership. Similar to --no-acl, this avoids issues with different user schemas between Heroku and Render.
-d "HEROKU_DATABASE_URL": Specifies the connection string for the database to be dumped. Enclose the URL in double quotes.
> your_heroku_dump.dump: Redirects the output of pg_dump to a file named your_heroku_dump.dump on your local machine.

This process might take some time depending on the size of your database. Once completed, you will have a file named your_heroku_dump.dump (or whatever you named it) in your current directory.

Step 3: Provision and Prepare Your Render PostgreSQL Database

If you haven’t already, provision a new PostgreSQL database instance on Render. Navigate to your Render dashboard, select “New” -> “PostgreSQL”, and follow the prompts to create your database. Choose a plan that meets your application’s needs.

Once your Render PostgreSQL database is provisioned and ready, navigate to its dashboard page. You will find the Internal Database URL and External Database URL. For this migration, we will typically use the External Database URL, which allows connection from outside Render’s internal network. Copy this URL, as it contains the host, port, user, password, and database name for your Render instance.

For example, a Render PostgreSQL URL might look like: postgres://user:password@external-host.render.com/database_name

Important: Ensure the target Render database is empty or suitable for overwriting. If you’re migrating to an existing Render database that contains data, you should back it up first, or clear it if you intend a full replacement.

Step 4: Import Data into Render PostgreSQL

Now, we will use pg_restore to import the data from your local dump file into the Render PostgreSQL database. This utility is designed to work with the custom format created by pg_dump -Fc.

Execute the following command, replacing RENDER_DATABASE_URL with the actual External Database URL for your Render Postgres instance, and your_heroku_dump.dump with the name of your backup file:

pg_restore --verbose --clean --no-acl --no-owner -d "RENDER_DATABASE_URL" your_heroku_dump.dump

Let’s explain these options:

--verbose: Provides detailed output during the restore process, which is helpful for monitoring progress and troubleshooting.
--clean: Drops any existing database objects (tables, functions, etc.) before recreating them. Use this if you are restoring into a database that might have remnants of previous structures. Use with caution if your Render database is not new or already contains data you wish to preserve.
--no-acl: Prevents restoring access privileges. This aligns with the --no-acl used during pg_dump and prevents permission conflicts.
--no-owner: Prevents restoring object ownership. This aligns with the --no-owner used during pg_dump and prevents ownership conflicts between Heroku and Render users.
-d "RENDER_DATABASE_URL": Specifies the connection string for the target Render database. Enclose the URL in double quotes.
your_heroku_dump.dump: The path to your backup file.

The import process will begin. Keep an eye on the output for any errors. If successful, you will see a series of messages indicating objects being created and data being restored.

Step 5: Verify Data and Update Application Configuration

After the import completes, it’s crucial to verify the integrity and completeness of your data on Render.

You can connect to your Render PostgreSQL database using psql and run some basic queries:

psql "RENDER_DATABASE_URL"

Once connected, try:

\dt
SELECT count(*) FROM your_largest_table;
SELECT * FROM a_critical_table LIMIT 5;

Compare the counts and sample data with your original Heroku database to ensure everything migrated correctly.

Finally, update your application on Render to point to the new PostgreSQL database. This typically involves updating environment variables. For a Render application, you would go to your service settings and update the DATABASE_URL (or similar variable) to your Render PostgreSQL Internal Database URL.

After updating the environment variables, deploy your application on Render. Once deployed, thoroughly test your application’s database interactions. If all tests pass, you can then disable maintenance mode on your Heroku application:

heroku maintenance:off -a your-heroku-app-name

Common Pitfalls

Network Connectivity & Firewalls: Ensure your local machine (where you run pg_dump and pg_restore) can reach both Heroku Postgres and Render PostgreSQL. Corporate firewalls or local security settings can sometimes block these connections.
User/Role Permissions Mismatch: Heroku creates its own user roles for databases. When migrating to Render, the target database will have its own primary user. Using --no-owner and --no-acl during both dump and restore largely mitigates this, but be aware of application-level permissions that might need adjustment.
pg_dump / pg_restore Version Incompatibility: While generally backward compatible, significant version differences (e.g., dumping from a Postgres 9.x to restoring into a 15.x database, though Heroku is typically newer) can cause issues. It’s best practice to use pg_dump and pg_restore versions that are equal to or newer than the source database, and ideally close to the target database version.
Large Database Sizes: For very large databases, the dump and restore process can take a significant amount of time and consume substantial local resources. Consider using cloud storage (e.g., S3) as an intermediate step if local storage or network speed is a bottleneck, or look into direct data transfer services if available.

Conclusion

Congratulations! You have successfully migrated your Heroku Postgres data to Render PostgreSQL. This migration not only helps you adapt to changing platform landscapes but also empowers you with greater control and potentially better cost efficiency for your database infrastructure.

By leveraging the robust capabilities of pg_dump and pg_restore, we’ve demonstrated how to perform a critical database migration with confidence. Remember to always verify your data thoroughly post-migration and continue to monitor your application’s performance on its new home.

TechResolve is committed to providing practical solutions for complex DevOps challenges. Stay tuned for more guides on optimizing your cloud infrastructure and enhancing your development workflows!