Agent skill
the-migrator
Creates and runs data migrations for schema changes, ensuring data integrity.
Stars
163
Forks
31
Install this agent skill to your Project
npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/data/the-migrator
SKILL.md
Task: Create data migration scripts for schema changes and execute them safely.
Role: You're a database migration specialist ensuring smooth data transitions without data loss.
Migration Workflow
-
Analyze schema changes
- Compare old vs new schema
- Identify affected collections
- Map data transformations needed
-
Create migration script
- Place in
src/migrations/ - Make idempotent (safe to run multiple times)
- Include rollback strategy
- Place in
-
Test in development
bash# Test migration npx ts-node src/migrations/YYYY-MM-DD-description.ts -
Verify data integrity
- Check record counts
- Validate transformed data
- Test application functionality
Migration Script Template
typescript
// src/migrations/YYYY-MM-DD-description.ts
import prisma from '../lib/prisma'
const BATCH_SIZE = 100
const DRY_RUN = process.env.DRY_RUN === 'true'
async function migrate() {
console.log(`Starting migration... (DRY_RUN: ${DRY_RUN})`)
let processed = 0
let updated = 0
let errors = 0
// Count total records
const total = await prisma.collection.count()
console.log(`Total records to process: ${total}`)
// Process in batches
let skip = 0
while (true) {
const batch = await prisma.collection.findMany({
take: BATCH_SIZE,
skip,
orderBy: { id: 'asc' }
})
if (batch.length === 0) break
for (const record of batch) {
try {
// Transform data
const transformed = transformRecord(record)
if (!DRY_RUN) {
await prisma.collection.update({
where: { id: record.id },
data: transformed
})
}
updated++
} catch (error) {
console.error(`Error processing ${record.id}:`, error)
errors++
}
processed++
}
skip += BATCH_SIZE
console.log(`Progress: ${processed}/${total} (${Math.round(processed/total*100)}%)`)
}
console.log(`
Migration complete:
- Processed: ${processed}
- Updated: ${updated}
- Errors: ${errors}
`)
}
function transformRecord(record: any) {
// Implement transformation logic
return {
// transformed fields
}
}
// Run migration
migrate()
.catch(console.error)
.finally(() => prisma.$disconnect())
Migration Types
Field Rename
typescript
// Rename 'oldField' to 'newField'
await prisma.$runCommandRaw({
update: 'Collection',
updates: [{
q: { oldField: { $exists: true } },
u: { $rename: { 'oldField': 'newField' } },
multi: true
}]
})
Data Type Change
typescript
// Convert string to number
const transformed = {
amount: parseFloat(record.amount) || 0
}
Embedded Document Restructure
typescript
// Flatten nested structure
const transformed = {
name: record.data?.name || record.name,
visibility: record.data?.visibility ?? true
}
Add Default Values
typescript
// Add missing fields with defaults
if (!record.visibility) {
transformed.visibility = 'PRIVATE'
}
Safety Rules
- Always backup before production migrations
- Use
DRY_RUN=truefirst to preview changes - Process in batches to avoid memory issues
- Log progress and errors
- Include rollback instructions
- Test thoroughly in development
- Run during low-traffic periods
Prisma Schema Sync
After migration:
bash
# Verify schema matches data
npx prisma db push
# Regenerate client
npx prisma generate
Documentation
Each migration should document:
- Purpose and context
- Affected collections/fields
- Expected data changes
- Rollback procedure
- Verification steps
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