Implemented PostgreSQL full-text search on the course table, added a tsvector generated column with GIN index, replaced the ILIKE '%query%' predicate with @@ plainto_tsquery, and added ts_rank relevance-based ordering. Removed an unused test import; entity unchanged since the column is DB-managed.

src/migrations/1763000000000-AddCourseFtsSearch.ts

@@ -0,0 +1,24 @@
+import { MigrationInterface, QueryRunner } from 'typeorm';
+
+export class AddCourseFtsSearch1763000000000 implements MigrationInterface {
+  name = 'AddCourseFtsSearch1763000000000';
+
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(`
+      ALTER TABLE "course"
+      ADD COLUMN IF NOT EXISTS "search_vector" tsvector
+      GENERATED ALWAYS AS (
+        to_tsvector('english', coalesce(title, '') || ' ' || coalesce(description, ''))
+      ) STORED
+    `);
+    await queryRunner.query(`
+      CREATE INDEX IF NOT EXISTS "IDX_course_search_vector"
+      ON "course" USING GIN ("search_vector")
+    `);
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query('DROP INDEX IF EXISTS "IDX_course_search_vector"');
+    await queryRunner.query('ALTER TABLE "course" DROP COLUMN IF EXISTS "search_vector"');
+  }
+}

src/search/search.service.spec.ts

@@ -3,7 +3,6 @@ import { Test, TestingModule } from '@nestjs/testing';
 import { ElasticsearchService as NestElasticsearchService } from '@nestjs/elasticsearch';
 import { getRepositoryToken } from '@nestjs/typeorm';
 import { SearchService } from './search.service';
-import { SEARCH_CONSTANTS } from './search.constants';
 import { Course } from '../courses/entities/course.entity';
 
 const mockQueryBuilder = {

src/search/search.service.ts

@@ -65,8 +65,8 @@ export class SearchService {
     try {
       const qb = this.courseRepository.createQueryBuilder('course');
       if (safeQuery) {
-        qb.where('course.title ILIKE :query OR course.description ILIKE :query', {
-          query: `%${safeQuery}%`,
+        qb.where("course.search_vector @@ plainto_tsquery('english', :query)", {
+          query: safeQuery,
         });
       }
 
@@ -83,6 +83,10 @@ export class SearchService {
       if (sort === 'price_asc') qb.orderBy('course.price', 'ASC');
       else if (sort === 'price_desc') qb.orderBy('course.price', 'DESC');
       else if (sort === 'newest') qb.orderBy('course.createdAt', 'DESC');
+      else if (sort === 'relevance')
+        qb.orderBy("ts_rank(course.search_vector, plainto_tsquery('english', :query))", 'DESC');
+      else if (safeQuery)
+        qb.orderBy("ts_rank(course.search_vector, plainto_tsquery('english', :query))", 'DESC');
       else qb.orderBy('course.createdAt', 'DESC');
 
       const skip = (page - 1) * limit;