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Database Migration

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Execute database migrations across ORMs and platforms with zero-downtime strategies, data transformation, and rollback procedures. Use when migrating databases, changing schemas, performing data transformations, or implementing zero-downtime deployment strategies.

Originally by wshobson · MIT

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Execute database migrations across ORMs and platforms with zero-downtime strategies, data transformation, and rollback procedures. Use when migrating databases, changing schemas, performing data transformations, or implementing zero-downtime deployment strategies.

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database-migration/SKILL.md334 lines8.0 KBRawView on GitHub
Frontmatter — 2 properties
namedatabase-migration
descriptionExecute database migrations across ORMs and platforms with zero-downtime strategies, data transformation, and rollback procedures. Use when migrating databases, changing schemas, performing data transformations, or implementing zero-downtime deployment strategies.
1---
2name: database-migration
3description: Execute database migrations across ORMs and platforms with zero-downtime strategies, data transformation, and rollback procedures. Use when migrating databases, changing schemas, performing data transformations, or implementing zero-downtime deployment strategies.
4---A5 — No allowed-tools declared — no way to tell what this skill may touch
5 
6# Database Migration
7 
8Master database schema and data migrations across ORMs (Sequelize, TypeORM, Prisma), including rollback strategies and zero-downtime deployments.
9 
10## When to Use This Skill
11 
12- Migrating between different ORMs
13- Performing schema transformations
14- Moving data between databases
15- Implementing rollback procedures
16- Zero-downtime deployments
17- Database version upgrades
18- Data model refactoring
19 
20## ORM Migrations
21 
22### Sequelize Migrations
23 
24```javascript
25// migrations/20231201-create-users.js
26module.exports = {
27 up: async (queryInterface, Sequelize) => {
28 await queryInterface.createTable("users", {
29 id: {
30 type: Sequelize.INTEGER,
31 primaryKey: true,
32 autoIncrement: true,
33 },
34 email: {
35 type: Sequelize.STRING,
36 unique: true,
37 allowNull: false,
38 },
39 createdAt: Sequelize.DATE,
40 updatedAt: Sequelize.DATE,
41 });
42 },
43 
44 down: async (queryInterface, Sequelize) => {
45 await queryInterface.dropTable("users");
46 },
47};
48 
49// Run: npx sequelize-cli db:migrate
50// Rollback: npx sequelize-cli db:migrate:undo
51```
52 
53### TypeORM Migrations
54 
55```typescript
56// migrations/1701234567-CreateUsers.ts
57import { MigrationInterface, QueryRunner, Table } from "typeorm";
58 
59export class CreateUsers1701234567 implements MigrationInterface {
60 public async up(queryRunner: QueryRunner): Promise<void> {
61 await queryRunner.createTable(
62 new Table({
63 name: "users",
64 columns: [
65 {
66 name: "id",
67 type: "int",
68 isPrimary: true,
69 isGenerated: true,
70 generationStrategy: "increment",
71 },
72 {
73 name: "email",
74 type: "varchar",
75 isUnique: true,
76 },
77 {
78 name: "created_at",
79 type: "timestamp",
80 default: "CURRENT_TIMESTAMP",
81 },
82 ],
83 }),
84 );
85 }
86 
87 public async down(queryRunner: QueryRunner): Promise<void> {
88 await queryRunner.dropTable("users");
89 }
90}
91 
92// Run: npm run typeorm migration:run
93// Rollback: npm run typeorm migration:revert
94```
95 
96### Prisma Migrations
97 
98```prisma
99// schema.prisma
100model User {
101 id Int @id @default(autoincrement())
102 email String @unique
103 createdAt DateTime @default(now())
104}
105 
106// Generate migration: npx prisma migrate dev --name create_users
107// Apply: npx prisma migrate deploy
108```
109 
110## Schema Transformations
111 
112### Adding Columns with Defaults
113 
114```javascript
115// Safe migration: add column with default
116module.exports = {
117 up: async (queryInterface, Sequelize) => {
118 await queryInterface.addColumn("users", "status", {
119 type: Sequelize.STRING,
120 defaultValue: "active",
121 allowNull: false,
122 });
123 },
124 
125 down: async (queryInterface) => {
126 await queryInterface.removeColumn("users", "status");
127 },
128};
129```
130 
131### Renaming Columns (Zero Downtime)
132 
133```javascript
134// Step 1: Add new column
135module.exports = {
136 up: async (queryInterface, Sequelize) => {
137 await queryInterface.addColumn("users", "full_name", {
138 type: Sequelize.STRING,
139 });
140 
141 // Copy data from old column
142 await queryInterface.sequelize.query("UPDATE users SET full_name = name");
143 },
144 
145 down: async (queryInterface) => {
146 await queryInterface.removeColumn("users", "full_name");
147 },
148};
149 
150// Step 2: Update application to use new column
151 
152// Step 3: Remove old column
153module.exports = {
154 up: async (queryInterface) => {
155 await queryInterface.removeColumn("users", "name");
156 },
157 
158 down: async (queryInterface, Sequelize) => {
159 await queryInterface.addColumn("users", "name", {
160 type: Sequelize.STRING,
161 });
162 },
163};
164```
165 
166### Changing Column Types
167 
168```javascript
169module.exports = {
170 up: async (queryInterface, Sequelize) => {
171 // For large tables, use multi-step approach
172 
173 // 1. Add new column
174 await queryInterface.addColumn("users", "age_new", {
175 type: Sequelize.INTEGER,
176 });
177 
178 // 2. Copy and transform data
179 await queryInterface.sequelize.query(`
180 UPDATE users
181 SET age_new = CAST(age AS INTEGER)
182 WHERE age IS NOT NULL
183 `);
184 
185 // 3. Drop old column
186 await queryInterface.removeColumn("users", "age");
187 
188 // 4. Rename new column
189 await queryInterface.renameColumn("users", "age_new", "age");
190 },
191 
192 down: async (queryInterface, Sequelize) => {
193 await queryInterface.changeColumn("users", "age", {
194 type: Sequelize.STRING,
195 });
196 },
197};
198```
199 
200## Data Transformations
201 
202### Complex Data Migration
203 
204```javascript
205module.exports = {
206 up: async (queryInterface, Sequelize) => {
207 // Get all records
208 const [users] = await queryInterface.sequelize.query(
209 "SELECT id, address_string FROM users",
210 );
211 
212 // Transform each record
213 for (const user of users) {
214 const addressParts = user.address_string.split(",");
215 
216 await queryInterface.sequelize.query(
217 `UPDATE users
218 SET street = :street,
219 city = :city,
220 state = :state
221 WHERE id = :id`,
222 {
223 replacements: {
224 id: user.id,
225 street: addressParts[0]?.trim(),
226 city: addressParts[1]?.trim(),
227 state: addressParts[2]?.trim(),
228 },
229 },
230 );
231 }
232 
233 // Drop old column
234 await queryInterface.removeColumn("users", "address_string");
235 },
236 
237 down: async (queryInterface, Sequelize) => {
238 // Reconstruct original column
239 await queryInterface.addColumn("users", "address_string", {
240 type: Sequelize.STRING,
241 });
242 
243 await queryInterface.sequelize.query(`
244 UPDATE users
245 SET address_string = CONCAT(street, ', ', city, ', ', state)
246 `);
247 
248 await queryInterface.removeColumn("users", "street");
249 await queryInterface.removeColumn("users", "city");
250 await queryInterface.removeColumn("users", "state");
251 },
252};
253```
254 
255## Rollback Strategies
256 
257### Transaction-Based Migrations
258 
259```javascript
260module.exports = {
261 up: async (queryInterface, Sequelize) => {
262 const transaction = await queryInterface.sequelize.transaction();
263 
264 try {
265 await queryInterface.addColumn(
266 "users",
267 "verified",
268 { type: Sequelize.BOOLEAN, defaultValue: false },
269 { transaction },
270 );
271 
272 await queryInterface.sequelize.query(
273 "UPDATE users SET verified = true WHERE email_verified_at IS NOT NULL",
274 { transaction },
275 );
276 
277 await transaction.commit();
278 } catch (error) {
279 await transaction.rollback();
280 throw error;
281 }
282 },
283 
284 down: async (queryInterface) => {
285 await queryInterface.removeColumn("users", "verified");
286 },
287};
288```
289 
290### Checkpoint-Based Rollback
291 
292```javascript
293module.exports = {
294 up: async (queryInterface, Sequelize) => {
295 // Create backup table
296 await queryInterface.sequelize.query(
297 "CREATE TABLE users_backup AS SELECT * FROM users",
298 );
299 
300 try {
301 // Perform migration
302 await queryInterface.addColumn("users", "new_field", {
303 type: Sequelize.STRING,
304 });
305 
306 // Verify migration
307 const [result] = await queryInterface.sequelize.query(
308 "SELECT COUNT(*) as count FROM users WHERE new_field IS NULL",
309 );
310 
311 if (result[0].count > 0) {
312 throw new Error("Migration verification failed");
313 }
314 
315 // Drop backup
316 await queryInterface.dropTable("users_backup");
317 } catch (error) {
318 // Restore from backup
319 await queryInterface.sequelize.query("DROP TABLE users");A1 — Drops a database table
320 await queryInterface.sequelize.query(
321 "CREATE TABLE users AS SELECT * FROM users_backup",
322 );
323 await queryInterface.dropTable("users_backup");
324 throw error;
325 }
326 },
327};
328```
329 
330## Additional patterns and templates
331 
332More detailed templates and worked examples live in `references/details.md`. Read that file for the full pattern library.
333 
334 

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