How to Is MySQL Cloud Hosted in PostgreSQL

Galaxy Glossary

Is MySQL cloud hosted and how can PostgreSQL query it?

Use mysql_fdw to access a cloud-hosted MySQL instance directly from PostgreSQL.

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Description

What does “cloud-hosted MySQL” mean?

Cloud-hosted MySQL refers to a managed MySQL server running on services such as Amazon RDS, Google Cloud SQL, or Azure Database for MySQL. The provider handles backups, scaling, and patches.

Can PostgreSQL query a cloud MySQL database?

Yes. Install the mysql_fdw extension, create a foreign server that points to the cloud host, and map remote tables so they appear local to PostgreSQL.

Why use mysql_fdw instead of ETL?

mysql_fdw keeps data live.Queries run in PostgreSQL always hit the latest rows in MySQL, eliminating batch pipelines and reducing latency.

How do I install `mysql_fdw`?

On most Linux distributions: sudo apt install postgresql-15-mysql-fdw or build from source. Restart PostgreSQL and verify with CREATE EXTENSION mysql_fdw;.

Do I need firewall rules?

Allow inbound traffic from your PostgreSQL server’s IP to the MySQL cloud instance on port 3306. Use TLS for encrypted transport.

What permissions are required on MySQL?

Create a service account with SELECT on the target schema.For write access, grant INSERT, UPDATE, or DELETE as needed.

Performance tips?

Push joins and filters to MySQL using the OPTIONS (use_remote_estimate 'true') clause. Add indexes on columns used in WHERE clauses.

Best practice for credentials?

Store the MySQL username and password in pgpass or use CREATE USER MAPPING with password_encrypted. Avoid hard-coding in SQL files.

How do I refresh foreign tables?

Run IMPORT FOREIGN SCHEMA again when new MySQL tables appear, or script periodic refreshes with cron.

Can I write back to MySQL?

Yes.Include OPTIONS (autocommit 'true') in the foreign table definition and ensure the FDW was compiled with write support.

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Why How to Is MySQL Cloud Hosted in PostgreSQL is important

How to Is MySQL Cloud Hosted in PostgreSQL Example Usage


-- Find top 5 customers by spend in cloud-hosted MySQL, directly in Postgres
SELECT c.name,
       SUM(o.total_amount) AS lifetime_value
FROM   Customers c
JOIN   Orders    o ON o.customer_id = c.id
GROUP  BY c.name
ORDER  BY lifetime_value DESC
LIMIT  5;

How to Is MySQL Cloud Hosted in PostgreSQL Syntax


-- 1. Enable the extension
CREATE EXTENSION IF NOT EXISTS mysql_fdw;

-- 2. Register the cloud MySQL server
CREATE SERVER ecommerce_mysql
    FOREIGN DATA WRAPPER mysql_fdw
    OPTIONS (
        host 'aws-mysql.c9xyabcd1234.us-east-1.rds.amazonaws.com',
        port '3306'
    );

-- 3. Map credentials
CREATE USER MAPPING FOR CURRENT_USER
    SERVER ecommerce_mysql
    OPTIONS (username 'readonly', password 'SECRET');

-- 4. Import the schema containing ecommerce tables
IMPORT FOREIGN SCHEMA ecommerce
    LIMIT TO (Customers, Orders, Products, OrderItems)
    FROM SERVER ecommerce_mysql INTO public;

-- 5. Query as if local
SELECT c.name, o.total_amount
FROM Customers c
JOIN Orders o ON o.customer_id = c.id
WHERE o.order_date >= CURRENT_DATE - INTERVAL '30 days';

Common Mistakes

Granting superuser rights to the FDW account. This violates least-privilege and exposes data. Instead, grant only the exact SELECT/INSERT/UPDATE/DELETE permissions required.
Forgetting to enable <code>use_remote_estimate</code>. Without it, the planner misestimates row counts and may pull huge datasets locally. Add the option to push filters to MySQL.

Frequently Asked Questions (FAQs)

Is mysql_fdw production ready?

Yes, many companies use it in production. Monitor query plans and stay current with releases.

Does mysql_fdw support prepared statements?

Yes. PostgreSQL sends prepared queries to MySQL, improving performance for repetitive workloads.

Can I replicate data instead of querying live?

Use logical replication tools like Debezium or AWS DMS if you need a local copy rather than live access.

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