drizzle-team/drizzle-orm · error · Error

Method not implemented.

Error message

Method not implemented.

What it means

PrismaMySqlPreparedQuery.iterator() throws 'Method not implemented.' because the Prisma bridge routes queries through prisma.$queryRawUnsafe, which returns a fully-materialized result and has no streaming protocol. Streaming cursors are therefore not wired through Prisma's client.

Source

Thrown at drizzle-orm/src/prisma/mysql/session.ts:20

import { entityKind } from '~/entity.ts';
import { type Logger, NoopLogger } from '~/logger.ts';
import type {
	MySqlDialect,
	MySqlPreparedQueryConfig,
	MySqlPreparedQueryHKT,
	MySqlQueryResultHKT,
	MySqlTransaction,
	MySqlTransactionConfig,
} from '~/mysql-core/index.ts';
import { MySqlPreparedQuery, MySqlSession } from '~/mysql-core/index.ts';
import { fillPlaceholders } from '~/sql/sql.ts';
import type { Query, SQL } from '~/sql/sql.ts';
import type { Assume } from '~/utils.ts';

export class PrismaMySqlPreparedQuery<T> extends MySqlPreparedQuery<MySqlPreparedQueryConfig & { execute: T }> {
	override iterator(_placeholderValues?: Record<string, unknown> | undefined): AsyncGenerator<unknown, any, unknown> {
		throw new Error('Method not implemented.');
	}
	static override readonly [entityKind]: string = 'PrismaMySqlPreparedQuery';

	constructor(
		private readonly prisma: PrismaClient,
		private readonly query: Query,
		private readonly logger: Logger,
	) {
		super(undefined, undefined, undefined);
	}

	override execute(placeholderValues?: Record<string, unknown>): Promise<T> {
		const params = fillPlaceholders(this.query.params, placeholderValues ?? {});
		this.logger.logQuery(this.query.sql, params);
		return this.prisma.$queryRawUnsafe(this.query.sql, ...params);
	}
}

View on GitHub (pinned to b7862528fd)

Solutions

1. Use .all() or .execute() instead of .iterator() and process the returned array.
2. Paginate with LIMIT/OFFSET or keyset pagination to bound memory.
3. Switch to a native Drizzle MySQL driver (mysql2) if streaming is a hard requirement.

Example fix

// before (throws)
for await (const row of db.select().from(t).prepare().iterator()) {}

// after
const rows = await db.select().from(t).all();
for (const row of rows) {}

import { entityKind } from 'drizzle-orm/entity';

function isPrismaMySqlPrepared(q: any): boolean {
  return q?.[entityKind] === 'PrismaMySqlPreparedQuery';
}

const rows = isPrismaMySqlPrepared(stmt)
  ? await stmt.all()
  : collectAsync(stmt.iterator());

function isPrismaMySqlPreparedQuery(q: unknown): boolean {
  return (q as any)?.[Symbol.for('drizzle:entityKind')] === 'PrismaMySqlPreparedQuery';
}

try {
  for await (const row of stmt.iterator()) { /* ... */ }
} catch (e) {
  if (e instanceof Error && e.message === 'Method not implemented.') {
    const rows = await stmt.all();
    for (const row of rows) { /* ... */ }
  } else throw e;
}

When it happens

Trigger: Calling .iterator() on any prepared query or select from a PrismaMySQLSession-backed Drizzle db (drizzle(prismaClient, { dialect: 'mysql' })). Using for-await on a Drizzle query object produced via the Prisma adapter.

Common situations: Using Drizzle on top of an existing Prisma datasource to keep Prisma's connection management, then attempting streaming for large exports or ETL. Code migrated from a native MySQL Drizzle driver.

Related errors

• Method not implemented.
• Method not implemented.
• Streaming is not supported by the MySql Proxy driver
• You have an empty array for "${name}" enum values
• Your "${f.path.join('->')}" field references a column "${tab

AI-assisted analysis of drizzle-team/drizzle-orm@b7862528fd (2026-08-03). Data as JSON: /data/errors/09fabe98d38d2f0a.json. Report an issue: GitHub.