MariaDB to PostgreSQL migration guide

IntoSQL reads a MariaDB dump and writes one PostgreSQL script with the same tables, columns, keys, indexes, foreign keys, defaults, counters, sequences, comments and rows. It reads the dump itself, without a database server, and lists in the report every value PostgreSQL can't hold as it is and every object it doesn't carry. The script loads on PostgreSQL 13 and later.

Convert in the browser: MariaDB to PostgreSQL opens the converter set up for this pair.

Dump for the best result#

Any dump from mariadb-dump, mysqldump, phpMyAdmin or Adminer from MariaDB 10.3 on works, as .sql or .sql.gz. These options keep more of your data:

mariadb-dump --default-character-set=utf8mb4 --hex-blob \
  --routines --triggers --events --single-transaction \
  shop | gzip > shop.sql.gz

• --default-character-set=utf8mb4 keeps emoji and other 4-byte characters. A dump made with utf8mb3 has already lost them, and the report says so (dump_lost_four_byte_chars).
• --hex-blob writes binary columns and VECTOR values as hexadecimal, which survives copying between systems.
• --routines --triggers --events add those objects to the dump, so the report can list them by name.

A dump made with --no-create-info still converts: the types are read from the values, and the report says the schema was missing (no_schema). MariaDB's JSON columns, which the dump writes as longtext with a json_valid check, are read as JSON again.

Convert#

In the browser, open MariaDB to PostgreSQL or the converter on the home page, drop the dump and choose PostgreSQL. It reads the file from your disk in pieces, twice, and writes the script as it goes, so the dump is never uploaded and its size isn't limited by memory. The desktop app does the same with the file on disk.

With the command line:

intosql inspect shop.sql.gz
intosql convert shop.sql.gz --to postgresql --output shop.postgresql.sql --report shop.report.json

inspect lists the tables, their rows and what won't be converted, without writing anything. convert writes the script and, with --report, the report as JSON.

Through the API, a dump converts like any other file: open a conversion with its name ending in .sql or .sql.gz and "output": {"dialect": "postgresql"}.

Load into PostgreSQL#

createdb shop
psql -v ON_ERROR_STOP=1 -d shop -f shop.postgresql.sql

The script creates the tables without keys, copies the rows with COPY, then adds keys, indexes, foreign keys and identities, so it loads fast and stops at the first error. Foreign keys are added as NOT VALID and then validated: a row that points to a missing row is named by its constraint instead of failing the load half way. Each identity continues after the highest id copied, or after the table's AUTO_INCREMENT when that is higher.

Or load it straight in#

intosql load and the desktop app load the dump into PostgreSQL without a script, with the same tables, keys and indexes the script creates:

intosql load shop.sql.gz --into postgres://ana@localhost/shop

It stops before writing anything when one of the dump's tables already exists. It loads in one transaction, so a failed load leaves nothing. Loading into a database server is part of IntoSQL Pro, with a 14-day trial. See Loading.

What isn't converted#

Views, triggers, stored procedures, functions and events are written in MariaDB's own language. They are listed in the report by kind and name, never dropped silently, so you can recreate them in PostgreSQL.

Data types#

MariaDB to PostgreSQL data types lists each type that changes in the script: what it becomes, why, and the report line.

Every other rule#

Generated from the engine, where each rule is decided.