MikroORM query profiling

This tutorial shows how to add the MikroORM collector to profile SQL queries in a NestJS application that uses PostgreSQL via @mikro-orm/nestjs.

Prerequisites

• @eleven-labs/nest-profiler installed and configured
• @mikro-orm/core, @mikro-orm/nestjs and a driver (e.g. @mikro-orm/postgresql) installed with a working MikroOrmModule.forRoot()

Step 1 — Install the package

pnpm add @eleven-labs/nest-profiler-mikro-orm

Step 2 — Register the collector

Add MikroOrmCollectorModule after MikroOrmModule in your root module:

import { MikroOrmModule } from '@mikro-orm/nestjs';
import { PostgreSqlDriver } from '@mikro-orm/postgresql';
import { MikroOrmCollectorModule } from '@eleven-labs/nest-profiler-mikro-orm';

@Module({
  imports: [
    MikroOrmModule.forRoot({ driver: PostgreSqlDriver /* ... */ }),
    ProfilerModule.forRoot({ isGlobal: true }),
    MikroOrmCollectorModule.forRoot({
      slowQueryThreshold: 100, // queries > 100ms are highlighted (default)
    }),
  ],
})
export class AppModule {}

No other configuration is needed — the collector wraps the MikroORM logger automatically and requires no debug flag.

Step 3 — Instrument your services with spans

Use startSpan() to add meaningful labels to the Timeline panel alongside your MikroORM calls:

import { ProfilerService } from '@eleven-labs/nest-profiler';
import { EntityManager } from '@mikro-orm/core';

@Injectable()
export class ProductsService {
  constructor(
    private readonly em: EntityManager,
    private readonly profiler: ProfilerService,
  ) {}

  async findAll(): Promise<Product[]> {
    const stop = this.profiler.startSpan('db.products.findAll');
    const result = await this.em.fork().find(Product, {}, { orderBy: { createdAt: 'DESC' } });
    stop();
    return result;
  }
}

Step 4 — Test it

Start your application and make a request that triggers a database query:

curl -i http://localhost:3000/products

Copy the X-Debug-Token from the response headers, open /_profiler/{token}, and click the Database tab.

You will see:

• Each SQL query with its type badge (SELECT, INSERT, …)
• Duration per query (MikroORM's measured took) with a bar chart indicator
• Slow queries highlighted in red
• Bound parameters

The Timeline panel shows the db.products.findAll span alongside other phases.

How it works

At module initialization the collector wraps MikroORM's Logger.logQuery. MikroORM's SQL connection always measures execution time and calls logQuery with the query, its parameters and the elapsed took; the collector records an entry into the CLS profile for the current request and delegates to the original logger only if you had query logging enabled. MikroOrmCollector.collect() then reads and returns those entries.

This captures all queries issued through the EntityManager, repositories and the QueryBuilder. Queries executed outside a request context (e.g., during module initialization) are silently ignored since there is no active CLS profile.