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3.4 KiB
3.4 KiB
title, impact, impactDescription, tags
| title | impact | impactDescription | tags |
|---|---|---|---|
| Use Caching Strategically | HIGH | Dramatically reduces database load and response times | performance, caching, redis, optimization |
Use Caching Strategically
Implement caching for expensive operations, frequently accessed data, and external API calls. Use NestJS CacheModule with appropriate TTLs and cache invalidation strategies. Don't cache everything - focus on high-impact areas.
Incorrect (no caching or caching everything):
// No caching for expensive, repeated queries
@Injectable()
export class ProductsService {
async getPopular(): Promise<Product[]> {
// Runs complex aggregation query EVERY request
return this.productsRepo
.createQueryBuilder('p')
.leftJoin('p.orders', 'o')
.select('p.*, COUNT(o.id) as orderCount')
.groupBy('p.id')
.orderBy('orderCount', 'DESC')
.limit(20)
.getMany();
}
}
// Cache everything without thought
@Injectable()
export class UsersService {
@CacheKey('users')
@CacheTTL(3600)
@UseInterceptors(CacheInterceptor)
async findAll(): Promise<User[]> {
// Caching user list for 1 hour is wrong if data changes frequently
return this.usersRepo.find();
}
}
Correct (strategic caching with proper invalidation):
// Setup caching module
@Module({
imports: [
CacheModule.registerAsync({
imports: [ConfigModule],
inject: [ConfigService],
useFactory: (config: ConfigService) => ({
stores: [new KeyvRedis(config.get('REDIS_URL'))],
ttl: 60 * 1000, // Default 60s
}),
}),
],
})
export class AppModule {}
// Manual caching for granular control
@Injectable()
export class ProductsService {
constructor(
@Inject(CACHE_MANAGER) private cache: Cache,
private productsRepo: ProductRepository,
) {}
async getPopular(): Promise<Product[]> {
const cacheKey = 'products:popular';
// Try cache first
const cached = await this.cache.get<Product[]>(cacheKey);
if (cached) return cached;
// Cache miss - fetch and cache
const products = await this.fetchPopularProducts();
await this.cache.set(cacheKey, products, 5 * 60 * 1000); // 5 min TTL
return products;
}
// Invalidate cache on changes
async updateProduct(id: string, dto: UpdateProductDto): Promise<Product> {
const product = await this.productsRepo.save({ id, ...dto });
await this.cache.del('products:popular'); // Invalidate
return product;
}
}
// Decorator-based caching with auto-interceptor
@Controller('categories')
@UseInterceptors(CacheInterceptor)
export class CategoriesController {
@Get()
@CacheTTL(30 * 60 * 1000) // 30 minutes - categories rarely change
findAll(): Promise<Category[]> {
return this.categoriesService.findAll();
}
@Get(':id')
@CacheTTL(60 * 1000) // 1 minute
@CacheKey('category')
findOne(@Param('id') id: string): Promise<Category> {
return this.categoriesService.findOne(id);
}
}
// Event-based cache invalidation
@Injectable()
export class CacheInvalidationService {
constructor(@Inject(CACHE_MANAGER) private cache: Cache) {}
@OnEvent('product.created')
@OnEvent('product.updated')
@OnEvent('product.deleted')
async invalidateProductCaches(event: ProductEvent) {
await Promise.all([
this.cache.del('products:popular'),
this.cache.del(`product:${event.productId}`),
]);
}
}
Reference: NestJS Caching