gh-djankies-claude-configs-prisma-6/skills/optimizing-query-performance/references/batch-operations.md

Batch Operations Guide

createMany vs Loop

SLOW (N database round-trips):

for (const userData of users) {
  await prisma.user.create({ data: userData })
}

FAST (1 database round-trip):

await prisma.user.createMany({
  data: users,
  skipDuplicates: true
})

Performance Gain: 50-100x faster for 1000+ records.

Limitations:

• createMany does NOT return created records
• Does NOT trigger middleware or relation cascades
• skipDuplicates skips on unique constraint violations (no error)

Batch Updates

SLOW:

for (const id of orderIds) {
  await prisma.order.update({
    where: { id },
    data: { status: 'shipped' }
  })
}

FAST:

await prisma.order.updateMany({
  where: { id: { in: orderIds } },
  data: { status: 'shipped' }
})

Note: updateMany returns count, not records.

Batch with Transactions

When you need returned records or relation handling:

await prisma.$transaction(
  users.map(userData =>
    prisma.user.create({ data: userData })
  )
)

Use Case: Creating related records where you need IDs for subsequent operations.

Trade-off: Slower than createMany but supports relations and returns records.

Batch Size Considerations

For very large datasets (100k+ records), chunk into batches:

const BATCH_SIZE = 1000

for (let i = 0; i < records.length; i += BATCH_SIZE) {
  const batch = records.slice(i, i + BATCH_SIZE)

  await prisma.record.createMany({
    data: batch,
    skipDuplicates: true
  })

  console.log(`Processed ${Math.min(i + BATCH_SIZE, records.length)}/${records.length}`)
}

Benefits:

• Progress visibility
• Memory efficiency
• Failure isolation (one batch fails, others succeed)