Data base indexing

README.md

@@ -138,7 +138,42 @@ TeachLink Backend provides secure and scalable APIs to power features such as:
 | File Upload   | Cloudinary                 |
 | Documentation | Swagger                    |
 
-## 🚀 Deployment
+## �️ Database
+
+### Index Strategy
+
+The application uses strategic database indexes to optimize query performance, especially for frequently accessed data and pagination operations.
+
+#### Single Column Indexes
+- **User.email**: Unique index for authentication lookups
+- **User.username**: Index for profile searches
+- **User.tenantId**: Index for multi-tenant queries
+- **Payment.status**: Index for payment status filtering
+- **Payment.userId**: Index for user payment history
+- **Payment.courseId**: Index for course revenue queries
+- **Subscription.status**: Index for active subscription queries
+- **Subscription.userId**: Index for user subscription management
+- **Course.status**: Index for published course listings
+- **Course.instructorId**: Index for instructor course queries
+- **Enrollment.userId**: Index for user enrollment history
+- **Enrollment.courseId**: Index for course enrollment counts
+- **Enrollment.status**: Index for active enrollment filtering
+- **CourseModule.courseId**: Index for course module queries
+- **Lesson.moduleId**: Index for module lesson queries
+
+#### Composite Indexes
+- **Enrollment (userId, status)**: Optimized for user enrollment status queries
+- **Enrollment (courseId, status)**: Optimized for course enrollment analytics
+- **Payment (userId, status)**: Optimized for user payment status filtering
+- **Subscription (userId, status)**: Optimized for user subscription status queries
+
+#### Performance Considerations
+- Indexes are added to foreign key columns to improve JOIN performance
+- Composite indexes support common query patterns (e.g., filtering by user + status)
+- Partial indexes are used where applicable for better selectivity
+- Index maintenance overhead is monitored to ensure write performance is not negatively impacted
+
+## �🚀 Deployment
 
 ### Prerequisites
 

src/app.module.ts

@@ -29,6 +29,9 @@
 import * as redisStore from 'cache-manager-redis-store';
 import { envValidationSchema } from './config/env.validation';
 import { HealthModule } from './health/health.module';
+import { ThrottlerModule } from '@nestjs/throttler';
+import { APP_GUARD } from '@nestjs/core';
+import { CustomThrottleGuard } from './common/guards/throttle.guard';
 
 @Module({
   imports: [
@@ -67,6 +70,20 @@
       host: process.env.REDIS_HOST || 'localhost',
       port: parseInt(process.env.REDIS_PORT || '6379'),
     }),
+    ThrottlerModule.forRootAsync({
+      imports: [ConfigModule],
+      useFactory: () => ({
+        ttl: parseInt(process.env.THROTTLE_TTL || '60'),
+        limit: parseInt(process.env.THROTTLE_LIMIT || '10'),
+        storage: {
+          type: 'redis',
+          options: {
+            host: process.env.REDIS_HOST || 'localhost',
+            port: parseInt(process.env.REDIS_PORT || '6379'),
+          },
+        },
+      }),
+    }),
     HealthModule,
     SyncModule,
     MediaModule,
@@ -88,6 +105,10 @@
       provide: APP_INTERCEPTOR,
       useClass: MonitoringInterceptor,
     },
+    {
+      provide: APP_GUARD,
+      useClass: CustomThrottleGuard,
+    },
   ],
 })
 export class AppModule {}

src/auth/auth.controller.ts

@@ -1,5 +1,6 @@
 import { Controller, Post, Body, UseGuards, Req } from '@nestjs/common';
 import { ApiBearerAuth, ApiOperation, ApiTags } from '@nestjs/swagger';
+import { Throttle } from '@nestjs/throttler';
 import { AuthService } from './auth.service';
 import {
   RegisterDto,
@@ -19,12 +20,14 @@ export class AuthController {
   constructor(private readonly authService: AuthService) {}
 
   @Post('register')
+  @Throttle({ default: { limit: 3, ttl: 3600000 } }) // 3 requests per hour
   @ApiOperation({ summary: 'Register a new user' })
   async register(@Body() registerDto: RegisterDto) {
     return this.authService.register(registerDto);
   }
 
   @Post('login')
+  @Throttle({ default: { limit: 5, ttl: 900000 } }) // 5 requests per 15 minutes
   @ApiOperation({ summary: 'Login user and get tokens' })
   async login(@Body() loginDto: LoginDto) {
     return this.authService.login(loginDto);

src/common/guards/throttle.guard.ts

@@ -24,16 +24,21 @@ export class CustomThrottleGuard extends ThrottlerGuard {
 
     this.logger.warn(`Rate limit exceeded: ip=${ip} method=${request.method} route=${route}`);
 
+    // Get throttle options from the decorator or default
+    const throttleOptions = this.getThrottleOptions(context);
+
     // Inject standard rate-limit headers so clients can back off gracefully
-    response.setHeader('Retry-After', '60');
-    response.setHeader('X-RateLimit-Exceeded', 'true');
+    response.setHeader('Retry-After', throttleOptions.ttl);
+    response.setHeader('X-RateLimit-Limit', throttleOptions.limit);
+    response.setHeader('X-RateLimit-Remaining', 0);
+    response.setHeader('X-RateLimit-Reset', Math.floor(Date.now() / 1000) + throttleOptions.ttl);
 
     throw new HttpException(
       {
         statusCode: HttpStatus.TOO_MANY_REQUESTS,
         error: 'Too Many Requests',
         message: 'You have exceeded the request rate limit. Please wait before retrying.',
-        retryAfterSeconds: 60,
+        retryAfterSeconds: throttleOptions.ttl,
       },
       HttpStatus.TOO_MANY_REQUESTS,
     );
@@ -44,4 +49,20 @@ export class CustomThrottleGuard extends ThrottlerGuard {
     if (typeof forwarded === 'string') return forwarded.split(',')[0].trim();
     return request.ip ?? request.socket?.remoteAddress ?? 'unknown';
   }
+
+  private getThrottleOptions(context: ExecutionContext): { limit: number; ttl: number } {
+    // Try to get throttle options from the decorator
+    const handler = context.getHandler();
+    const throttleDecorator = Reflect.getMetadata('__throttler__', handler);
+
+    if (throttleDecorator) {
+      return {
+        limit: throttleDecorator.limit || 10,
+        ttl: throttleDecorator.ttl || 60,
+      };
+    }
+
+    // Fallback to default options
+    return { limit: 10, ttl: 60 };
+  }
 }

src/config/env.validation.ts

@@ -14,5 +14,8 @@ export const envValidationSchema = Joi.object({
   REDIS_HOST: Joi.string().required(),
   REDIS_PORT: Joi.number().required(),
 
+  THROTTLE_TTL: Joi.number().default(60),
+  THROTTLE_LIMIT: Joi.number().default(10),
+
   JWT_SECRET: Joi.string().min(10).required(),
 });

src/courses/entities/course-module.entity.ts

@@ -1,4 +1,4 @@
-import { Entity, PrimaryGeneratedColumn, Column, ManyToOne, OneToMany } from 'typeorm';
+import { Entity, PrimaryGeneratedColumn, Column, ManyToOne, OneToMany, Index } from 'typeorm';
 import { Course } from './course.entity';
 import { Lesson } from './lesson.entity';
 
@@ -16,6 +16,10 @@ export class CourseModule {
   @ManyToOne(() => Course, (course) => course.modules, { onDelete: 'CASCADE' })
   course: Course;
 
+  @Column({ name: 'course_id' })
+  @Index()
+  courseId: string;
+
   @OneToMany(() => Lesson, (lesson) => lesson.module)
   lessons: Lesson[];
 }

src/courses/entities/course.entity.ts

@@ -6,6 +6,7 @@ import {
   UpdateDateColumn,
   ManyToOne,
   OneToMany,
+  Index,
 } from 'typeorm';
 import { User } from '../../users/entities/user.entity';
 import { CourseModule } from './course-module.entity';
@@ -26,6 +27,7 @@ export class Course {
   price: number;
 
   @Column({ default: 'draft' }) // draft, published, archived
+  @Index()
   status: string;
 
   @Column({ nullable: true })
@@ -34,6 +36,10 @@ export class Course {
   @ManyToOne(() => User, (user) => user.courses)
   instructor: User;
 
+  @Column({ name: 'instructor_id' })
+  @Index()
+  instructorId: string;
+
   @OneToMany(() => CourseModule, (module) => module.course)
   modules: CourseModule[];
 

src/courses/entities/enrollment.entity.ts

@@ -5,25 +5,37 @@ import {
   ManyToOne,
   CreateDateColumn,
   UpdateDateColumn,
+  Index,
 } from 'typeorm';
 import { User } from '../../users/entities/user.entity';
 import { Course } from './course.entity';
 
 @Entity()
+@Index(['userId', 'status'])
+@Index(['courseId', 'status'])
 export class Enrollment {
   @PrimaryGeneratedColumn('uuid')
   id: string;
 
   @ManyToOne(() => User, (user) => user.enrollments, { onDelete: 'CASCADE' })
   user: User;
 
+  @Column({ name: 'user_id' })
+  @Index()
+  userId: string;
+
   @ManyToOne(() => Course, (course) => course.enrollments, { onDelete: 'CASCADE' })
   course: Course;
 
+  @Column({ name: 'course_id' })
+  @Index()
+  courseId: string;
+
   @Column({ type: 'float', default: 0 })
   progress: number; // 0 to 100
 
   @Column({ default: 'active' }) // active, completed, dropped
+  @Index()
   status: string;
 
   @CreateDateColumn()

src/courses/entities/lesson.entity.ts

@@ -1,4 +1,4 @@
-import { Entity, PrimaryGeneratedColumn, Column, ManyToOne } from 'typeorm';
+import { Entity, PrimaryGeneratedColumn, Column, ManyToOne, Index } from 'typeorm';
 import { CourseModule } from './course-module.entity';
 
 @Entity()
@@ -23,4 +23,8 @@ export class Lesson {
 
   @ManyToOne(() => CourseModule, (module) => module.lessons, { onDelete: 'CASCADE' })
   module: CourseModule;
+
+  @Column({ name: 'module_id' })
+  @Index()
+  moduleId: string;
 }

src/payments/entities/payment.entity.ts

@@ -6,6 +6,7 @@ import {
   UpdateDateColumn,
   ManyToOne,
   JoinColumn,
+  Index,
 } from 'typeorm';
 import { User } from '../../users/entities/user.entity';
 import { Course } from '../../courses/entities/course.entity';
@@ -28,6 +29,7 @@ export enum PaymentMethod {
 }
 
 @Entity('payments')
+@Index(['userId', 'status'])
 export class Payment {
   @PrimaryGeneratedColumn('uuid')
   id: string;
@@ -39,6 +41,7 @@ export class Payment {
   currency: string;
 
   @Column({ type: 'enum', enum: PaymentStatus, default: PaymentStatus.PENDING })
+  @Index()
   status: PaymentStatus;
 
   @Column({ type: 'enum', enum: PaymentMethod })
@@ -58,13 +61,15 @@ export class Payment {
   user: User;
 
   @Column({ name: 'user_id' })
+  @Index()
   userId: string;
 
   @ManyToOne(() => Course, (course) => course.id)
   @JoinColumn({ name: 'course_id' })
   course: Course;
 
   @Column({ name: 'course_id', nullable: true })
+  @Index()
   courseId: string;
 
   @Column({ type: 'boolean', default: false })

src/payments/entities/subscription.entity.ts

@@ -6,6 +6,7 @@ import {
   UpdateDateColumn,
   ManyToOne,
   JoinColumn,
+  Index,
 } from 'typeorm';
 import { User } from '../../users/entities/user.entity';
 
@@ -26,6 +27,7 @@ export enum SubscriptionInterval {
 }
 
 @Entity('subscriptions')
+@Index(['userId', 'status'])
 export class Subscription {
   @PrimaryGeneratedColumn('uuid')
   id: string;
@@ -34,6 +36,7 @@ export class Subscription {
   providerSubscriptionId: string;
 
   @Column({ type: 'enum', enum: SubscriptionStatus, default: SubscriptionStatus.ACTIVE })
+  @Index()
   status: SubscriptionStatus;
 
   @Column({ type: 'enum', enum: SubscriptionInterval })
@@ -68,6 +71,7 @@ export class Subscription {
   user: User;
 
   @Column({ name: 'user_id' })
+  @Index()
   userId: string;
 
   @CreateDateColumn()

src/payments/payments.controller.ts

@@ -11,6 +11,7 @@ import {
   HttpStatus,
 } from '@nestjs/common';
 import { ApiTags, ApiOperation, ApiResponse, ApiBearerAuth } from '@nestjs/swagger';
+import { Throttle } from '@nestjs/throttler';
 import { PaymentsService } from './payments.service';
 import { JwtAuthGuard } from '../auth/guards/jwt-auth.guard';
 import { RolesGuard } from '../auth/guards/roles.guard';
@@ -27,6 +28,7 @@ export class PaymentsController {
   constructor(private readonly paymentsService: PaymentsService) {}
 
   @Post('create-intent')
+  @Throttle({ default: { limit: 10, ttl: 3600000 } }) // 10 requests per hour
   @Roles(UserRole.STUDENT, UserRole.TEACHER)
   @ApiOperation({ summary: 'Create a payment intent for course purchase' })
   @ApiResponse({ status: 201, description: 'Payment intent created' })
@@ -35,6 +37,7 @@ export class PaymentsController {
   }
 
   @Post('subscriptions')
+  @Throttle({ default: { limit: 5, ttl: 3600000 } }) // 5 requests per hour
   @Roles(UserRole.STUDENT, UserRole.TEACHER)
   @ApiOperation({ summary: 'Create a subscription for premium course' })
   @ApiResponse({ status: 201, description: 'Subscription created' })