D1 Drizzle Schema

Generate correct Drizzle ORM schemas for Cloudflare D1. D1 is SQLite-based but has important differences that cause subtle bugs if you use standard SQLite patterns. This skill produces schemas that work correctly with D1's constraints.

Critical D1 Differences

Feature	Standard SQLite	D1
Foreign keys	OFF by default	Always ON (cannot disable)
Boolean type	No	No — use integer({ mode: 'boolean' })
Datetime type	No	No — use integer({ mode: 'timestamp' })
Max bound params	~999	100 (affects bulk inserts)
JSON support	Extension	Always available (json_extract, ->, ->>)
Concurrency	Multi-writer	Single-threaded (one query at a time)

Workflow

Step 1: Describe the Data Model

Gather requirements: what tables, what relationships, what needs indexing. If working from an existing description, infer the schema directly.

Step 2: Generate Drizzle Schema

Create schema files using D1-correct column patterns:

import { sqliteTable, text, integer, real, index, uniqueIndex } from 'drizzle-orm/sqlite-core'

export const users = sqliteTable('users', {
  // UUID primary key (preferred for D1)
  id: text('id').primaryKey().$defaultFn(() => crypto.randomUUID()),

  // Text fields
  name: text('name').notNull(),
  email: text('email').notNull(),

  // Enum (stored as TEXT, validated at schema level)
  role: text('role', { enum: ['admin', 'editor', 'viewer'] }).notNull().default('viewer'),

  // Boolean (D1 has no BOOL — stored as INTEGER 0/1)
  emailVerified: integer('email_verified', { mode: 'boolean' }).notNull().default(false),

  // Timestamp (D1 has no DATETIME — stored as unix seconds)
  createdAt: integer('created_at', { mode: 'timestamp' }).notNull().$defaultFn(() => new Date()),
  updatedAt: integer('updated_at', { mode: 'timestamp' }).notNull().$defaultFn(() => new Date()),

  // Typed JSON (stored as TEXT, Drizzle auto-serialises)
  preferences: text('preferences', { mode: 'json' }).$type<UserPreferences>(),

  // Foreign key (always enforced in D1)
  organisationId: text('organisation_id').references(() => organisations.id, { onDelete: 'cascade' }),
}, (table) => ({
  emailIdx: uniqueIndex('users_email_idx').on(table.email),
  orgIdx: index('users_org_idx').on(table.organisationId),
}))

See references/column-patterns.md for the full type reference.

Step 3: Add Relations

Drizzle relations are query builder helpers (separate from FK constraints):

import { relations } from 'drizzle-orm'

export const usersRelations = relations(users, ({ one, many }) => ({
  organisation: one(organisations, {
    fields: [users.organisationId],
    references: [organisations.id],
  }),
  posts: many(posts),
}))

Step 4: Export Types

export type User = typeof users.$inferSelect
export type NewUser = typeof users.$inferInsert

Step 5: Set Up Drizzle Config

Copy assets/drizzle-config-template.ts to drizzle.config.ts and update the schema path.

Step 6: Add Migration Scripts

Add to package.json:

{
  "db:generate": "drizzle-kit generate",
  "db:migrate:local": "wrangler d1 migrations apply DB --local",
  "db:migrate:remote": "wrangler d1 migrations apply DB --remote"
}

Always run on BOTH local AND remote before testing.

Step 7: Generate DATABASE_SCHEMA.md

Document the schema for future sessions:

• Tables with columns, types, and constraints
• Relationships and foreign keys
• Indexes and their purpose
• Migration workflow

Bulk Insert Pattern

D1 limits bound parameters to 100. Calculate batch size:

const BATCH_SIZE = Math.floor(100 / COLUMNS_PER_ROW)
for (let i = 0; i < rows.length; i += BATCH_SIZE) {
  await db.insert(table).values(rows.slice(i, i + BATCH_SIZE))
}

D1 Runtime Usage

import { drizzle } from 'drizzle-orm/d1'
import * as schema from './schema'

// In Worker fetch handler:
const db = drizzle(env.DB, { schema })

// Query patterns
const all = await db.select().from(schema.users).all()           // Array<User>
const one = await db.select().from(schema.users).where(eq(schema.users.id, id)).get()  // User | undefined
const count = await db.select({ count: sql`count(*)` }).from(schema.users).get()

Reference Files

When	Read
D1 vs SQLite, JSON queries, limits	references/d1-specifics.md
Column type patterns for Drizzle + D1	references/column-patterns.md

Assets

File	Purpose
assets/drizzle-config-template.ts	Starter drizzle.config.ts for D1
assets/schema-template.ts	Example schema with all common D1 patterns