fix(core): Fix DB migrations for MySQL

[burivuhster]

Summary

This PR address couple of DB migration issues, preventing n8n to start when using MySQL as a database

Column check constraint

Migration AddStatsColumnsToTestRun1736172058779 introduced some column check constraints, but referencing other columns in check condition of a column check constraint is not supported by MySQL (checked on 8.0.29, 8.0.41, 8.4.4).

Starting migration AddStatsColumnsToTestRun1736172058779
query failed: ALTER TABLE `test_run` ADD COLUMN `totalCases` INT CHECK(
				CASE
					WHEN status = 'new' THEN `totalCases` IS NULL
					WHEN status in ('cancelled', 'error') THEN `totalCases` IS NULL OR `totalCases` >= 0
					ELSE `totalCases` >= 0
				END
			)
error: Error: Column check constraint 'test_run_chk_1' references other column.

Solution

As those stats columns are soon to be removed anyway, created a separate migration file for MySQL under same migration name, without the check constraints. This change will not affect existing instances where the migration applied successfully, but only instances powered by MySQL, where this migration could not be applied.

Incomplete migration of PK type

The migration MigrateTestDefinitionKeyToString1731582748663 implementation for MySQL was incomplete. Although it run successfully, the queries for assigning new Primary Key and deleting temporary one was missing. This left the table test_definition in an inconsistent state (no PK), which prevented the next migration CreateTestMetricTable1732271325258 from running properly on MySQL 8.4.4:

Starting migration CreateTestMetricTable1732271325258
query failed: CREATE TABLE `test_metric` (`id` varchar(36) NOT NULL, `name` varchar(255) NOT NULL, `testDefinitionId` varchar(36) NOT NULL, `createdAt` datetime(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3), `updatedAt` datetime(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3), INDEX `IDX_3a4e9cf37111ac3270e2469b47` (`testDefinitionId`), CONSTRAINT `FK_3a4e9cf37111ac3270e2469b475` FOREIGN KEY (`testDefinitionId`) REFERENCES `test_definition` (`id`) ON DELETE CASCADE, PRIMARY KEY (`id`)) ENGINE=InnoDB
error: Error: Failed to add the foreign key constraint. Missing unique key for constraint 'FK_3a4e9cf37111ac3270e2469b475' in the referenced table 'test_definition'

Solution

Missing operations were added to the MigrateTestDefinitionKeyToString1731582748663 migration.
For those instances where the incomplete migration was already applied, the same operations were added to the subsequent migration CreateTestMetricTable1732271325258 conditionally.
Also FixTestDefinitionPrimaryKey1739873751194 migration was added to fix the primary column if it has not been fixed yet by the patched MigrateTestDefinitionKeyToString1731582748663 or CreateTestMetricTable1732271325258 migrations.

Added DB tests

To avoid issues like this in future, a new job for running tests using MySQL was added to a CI config.

Related Linear tickets, Github issues, and Community forum posts

• Initial DB migration fails on MySQL/MariaDB when running n8n in the Docker image #12836
• https://linear.app/n8n/issue/AI-644/failing-mysql-db-migration

Review / Merge checklist

• PR title and summary are descriptive. (conventions)
• Docs updated or follow-up ticket created.
• Tests included.
• PR Labeled with release/backport (if the PR is an urgent fix that needs to be backported)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

📢 Thoughts on this report? Let us know!

[tomi]

Thank you for fixing this and adding the new targets to the DB tests ❤️

[cypress]

n8n    Run #9318

Run Properties:   Passed #9318  •  32db13585d: 🌳 🖥️ browsers:node18.12.0-chrome107 🤖 burivuhster 🗃️ e2e/*

Project	n8n
Branch Review	ai-644-failing-mysql-db-migration
Run status	Passed #9318
Run duration	04m 27s
Commit	32db13585d: 🌳 🖥️ browsers:node18.12.0-chrome107 🤖 burivuhster 🗃️ e2e/*
Committer	Eugene Molodkin
View all properties for this run ↗︎

---

Test results
Failures	0
Flaky	1
Pending	5
Skipped	0
Passing	436
View all changes introduced in this branch ↗︎

[github-actions]

✅ All Cypress E2E specs passed

[burivuhster]

@tomi I was running some tests locally and found there are still cases, where primary key fix might not be applied (when all previous migrations were applied "successfully" before patch). I added a separate conditional migration to account for that. Tested on mysql 8.0.29 and 8.4, mariadb 10.5, each for both applying all migrations at once (same as in CI pipeline), and applying migrations from master branch first, then switching to this branch and applying all the fixes.

[github-actions]

✅ All Cypress E2E specs passed