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src/db/db.module.ts

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+import { Global, Module } from '@nestjs/common';
+import { DbService } from './db.service';
+
+@Global()
+@Module({
+  providers: [DbService],
+  exports: [DbService],
+})
+export class DbModule {}

src/db/db.service.ts

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+import { Injectable, OnModuleDestroy, OnModuleInit } from '@nestjs/common';
+import { ConfigService } from '@nestjs/config';
+import { Pool, QueryResult, QueryResultRow } from 'pg';
+import { getIntegerConfig } from '../common/config-number';
+
+type DatabaseHealth = {
+  now: Date;
+  timescaledb_installed: boolean;
+  timescaledb_version: string | null;
+};
+
+@Injectable()
+export class DbService implements OnModuleInit, OnModuleDestroy {
+  private pool!: Pool;
+
+  constructor(private readonly config: ConfigService) {}
+
+  /** Создает пул PostgreSQL и проверяет БД до начала обработки запросов. */
+  async onModuleInit(): Promise<void> {
+    const connectionString = this.config.get<string>('DATABASE_URL');
+    if (!connectionString) {
+      throw new Error('DATABASE_URL is required.');
+    }
+
+    this.pool = new Pool({
+      connectionString,
+      max: getIntegerConfig(this.config, 'PG_POOL_MAX', 20),
+      idleTimeoutMillis: 30_000,
+      connectionTimeoutMillis: 5_000,
+      statement_timeout: 60_000,
+      query_timeout: 60_000,
+      application_name: 'drill-cloud-v3',
+    });
+
+    await this.health();
+  }
+
+  /** Закрывает пул PostgreSQL при остановке Nest-приложения. */
+  async onModuleDestroy(): Promise<void> {
+    await this.pool?.end();
+  }
+
+  /** Выполняет параметризованный SQL-запрос через общий пул PostgreSQL. */
+  query<T extends QueryResultRow = QueryResultRow>(
+    text: string,
+    values: readonly unknown[] = [],
+  ): Promise<QueryResult<T>> {
+    return this.pool.query<T>(text, [...values]);
+  }
+
+  /** Возвращает легкий health-снимок БД, включая статус расширения TimescaleDB. */
+  async health(): Promise<DatabaseHealth> {
+    const result = await this.query<DatabaseHealth>(`
+      SELECT
+        now(),
+        ext.extversion IS NOT NULL AS timescaledb_installed,
+        ext.extversion AS timescaledb_version
+      FROM (SELECT 1) AS probe
+      LEFT JOIN pg_extension AS ext
+        ON ext.extname = 'timescaledb'
+    `);
+
+    return result.rows[0];
+  }
+}