🐛 Add Migration for MySQL to certify that we're using the correct collation (#1905)

* Migration for MySQL to certify that we're using the correct collation

* Update migration to check for collation existence before running

* ⚡ Fix format

Co-authored-by: Jan Oberhauser <jan.oberhauser@gmail.com>

packages/cli/src/databases/mysqldb/migrations/1623936588000-CertifyCorrectCollation.ts

@@ -0,0 +1,44 @@
+import { MigrationInterface, QueryRunner } from 'typeorm';
+import config = require('../../../../config');
+
+export class CertifyCorrectCollation1623936588000 implements MigrationInterface {
+	name = 'CertifyCorrectCollation1623936588000';
+
+	async up(queryRunner: QueryRunner): Promise<void> {
+		const tablePrefix = config.get('database.tablePrefix');
+		const databaseType = config.get('database.type');
+
+		if (databaseType === 'mariadb') {
+			// This applies to MySQL only.
+			return;
+		}
+
+		const checkCollationExistence = await queryRunner.query(`show collation where collation like 'utf8mb4_0900_ai_ci';`);
+		let collation = 'utf8mb4_general_ci';
+		if (checkCollationExistence.length > 0) {
+			collation = 'utf8mb4_0900_ai_ci';
+		}
+
+		const databaseName = config.get(`database.mysqldb.database`);
+
+		await queryRunner.query(`ALTER DATABASE \`${databaseName}\` CHARACTER SET utf8mb4 COLLATE ${collation};`);
+
+		for (const tableName of [
+			'credentials_entity',
+			'execution_entity',
+			'tag_entity',
+			'webhook_entity',
+			'workflow_entity',
+			'workflows_tags',
+		]) {
+			await queryRunner.query(`ALTER TABLE ${tablePrefix}${tableName} CONVERT TO CHARACTER SET utf8mb4 COLLATE ${collation};`);
+		}
+	}
+
+	async down(queryRunner: QueryRunner): Promise<void> {
+		// There is nothing to undo in this case as we already expect default collation to be utf8mb4
+		// This migration exists simply to enforce that n8n will work with
+		// older mysql versions
+	}
+
+}

packages/cli/src/databases/mysqldb/migrations/index.ts

@@ -7,6 +7,7 @@ import { ChangeDataSize1615306975123 } from './1615306975123-ChangeDataSize';
 import { ChangeCredentialDataSize1620729500000 } from './1620729500000-ChangeCredentialDataSize';
 import { CreateTagEntity1617268711084 } from './1617268711084-CreateTagEntity';
 import { UniqueWorkflowNames1620826335440 } from './1620826335440-UniqueWorkflowNames';
+import { CertifyCorrectCollation1623936588000 } from './1623936588000-CertifyCorrectCollation';
 
 export const mysqlMigrations = [
 	InitialMigration1588157391238,
@@ -18,4 +19,5 @@ export const mysqlMigrations = [
 	ChangeCredentialDataSize1620729500000,
 	CreateTagEntity1617268711084,
 	UniqueWorkflowNames1620826335440,
+	CertifyCorrectCollation1623936588000,
 ];