How to Migrate from Postgres to MySQL in PostgreSQL

Galaxy Glossary

How do I migrate data from PostgreSQL to MySQL without data loss?

Migrate Postgres schemas & data into a MySQL database using pg_dump, pgloader, and MySQL import utilities.

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Description

Example H2

Example H3

Why do teams migrate from PostgreSQL to MySQL?

Performance on read-heavy workloads, MySQL-native tooling, and organizational standards often drive migrations. Galaxy users moving reporting workloads can simplify their stack by consolidating on MySQL.

What tools can I use?

Most engineers rely on pg_dump + mysql, pgloader, or third-party SaaS services. pg_dump offers full control, pgloader automates type mapping, and SaaS tools add change-data-capture.

How do I create a MySQL-compatible dump with pg_dump?

Use pg_dump with --column-inserts and plain text format.Pipe the output through a small sed script or a tool like pg2mysql to translate PostgreSQL-specific syntax.

Step-by-step command sequence

1. Freeze writes on Postgres.
2. Run pg_dump to export schema and data.
3. Transform SQL to MySQL dialect.
4. Load into MySQL with mysql CLI.
5.Validate row counts and constraints.

How do I migrate sample ecommerce tables?

Dump the Customers, Orders, Products, and OrderItems tables, transform SERIAL to AUTO_INCREMENT, map BOOLEAN to TINYINT(1), and adjust timestamp defaults.

How do I import the dump into MySQL?

Use the mysql client: mysql -h mysql_host -u user -p ecommerce < dump_mysql.sql. Create the destination database beforehand if it does not exist.

How do I verify migrated data?

Run COUNT(*) on each table in both databases. For example: SELECT COUNT(*) FROM Customers;.Differences should be zero before cutting over traffic.

Best practices for seamless migration

Perform a test run in staging, script every step, disable foreign-key checks during import for speed, and keep the old Postgres instance read-only for a grace period.

What are common pitfalls?

Type mismatches (e.g., Postgres TEXT to MySQL VARCHAR) and identifier case sensitivity cause most failures. Address them in a mapping file or pgloader rules.

How do I cut over production traffic?

Use dual-write application logic or a brief maintenance window.Point application connections to MySQL once data parity is confirmed.

Why How to Migrate from Postgres to MySQL in PostgreSQL is important

How to Migrate from Postgres to MySQL in PostgreSQL Example Usage


pgloader --type "Customers,Orders,Products,OrderItems" --cast "type boolean to tinyint drop default" \
        postgres://admin:secret@pg_host/ecommerce_db \
        mysql://root:secret@mysql_host/ecommerce

How to Migrate from Postgres to MySQL in PostgreSQL Syntax


# Using pg_dump + mysql
pg_dump -h {PG_HOST} -U {PG_USER} -t Customers -t Orders -t Products -t OrderItems \
        --column-inserts --data-only ecommerce_db > dump_pg.sql
# Transform dump_pg.sql to MySQL dialect (pg2mysql, sed, or manual edits)
# Import into MySQL
docker exec -i mysql_container mysql -u root -p$MYSQL_PWD ecommerce < dump_mysql.sql

# Using pgloader (single command)
pgloader --with "quote identifiers" \
        postgres://pguser:pgpwd@pg_host/ecommerce_db \
        mysql://mysqluser:mysqlpwd@mysql_host/ecommerce?useSSL=false

Common Mistakes

Skipping data-type mapping. Postgres text arrays or JSONB do not have direct MySQL equivalents. Fix by casting to TEXT or using LONGTEXT/JSON columns during migration.
Forgetting to disable foreign-key checks during bulk import, causing constraint failures. Add <code>SET FOREIGN_KEY_CHECKS=0;</code> before import and re-enable afterward.