Import MySQL dump to PostgreSQL database

Question

How can I import an \"xxxx.sql\" dump from MySQL to a PostgreSQL database?

Answer 1

With pgloader

Get a recent version of pgloader; the one provided by Debian Jessie (as of 2019-01-27) is 3.1.0 and won't work since pgloader will error with

Can not find file mysql://...
Can not find file postgres://...

Access to MySQL source

First, make sure you can establish a connection to mysqld on the server running MySQL using

telnet theserverwithmysql 3306

If that fails with

Name or service not known

log in to theserverwithmysql and edit the configuration file of mysqld. If you don't know where the config file is, use find / -name mysqld.cnf.

In my case I had to change this line of mysqld.cnf

# By default we only accept connections from localhost
bind-address    = 127.0.0.1

to

bind-address    = *

Mind that allowing access to your MySQL database from all addresses can pose a security risk, meaning you probably want to change that value back after the database migration.

Make the changes to mysqld.cnf effective by restarting mysqld.

Preparing the Postgres target

Assuming you are logged in on the system that runs Postgres, create the database with

createdb databasename

The user for the Postgres database has to have sufficient privileges to create the schema, otherwise you'll run into

permission denied for database databasename

when calling pgloader. I got this error although the user had the right to create databases according to psql > \du.

You can make sure of that in psql:

GRANT ALL PRIVILEGES ON DATABASE databasename TO otherusername;

Again, this might be privilege overkill and thus a security risk if you leave all those privileges with user otherusername.

Migrate

Finally, the command

pgloader mysql://theusername:thepassword@theserverwithmysql/databasename postgresql://otherusername@localhost/databasename

executed on the machine running Postgres should produce output that ends with a line like this:

Total import time          ✓     877567   158.1 MB       1m11.230s