Initial commit: Complete Software Architecture course with 11 modules

- Added comprehensive course structure with 11 modules - Included theoretical content, practical examples, and tasks - Multi-language code examples (Java, Rust, Node.js, Python) - Detailed analysis of architectural approaches and trade-offs - Complete caching strategies documentation - Architecture examples from real-world systems (Twitter, Netflix, Uber) - Structured navigation and learning path - Ready for educational use
2025-09-09 22:08:07 +03:00
commit 15e744da49
@@ -0,0 +1,145 @@
+# Оптимизация базы данных
+
+## Навигация
+- [🏠 Главная страница курса](../../../README.md)
+- [📚 Модуль 10](../README.md)
+
+---
+
+## Оптимизация запросов
+
+### 1. Query Optimization
+```sql
+-- Оптимизация запросов
+-- Плохо: медленный запрос
+SELECT * FROM users u 
+JOIN orders o ON u.id = o.user_id 
+WHERE u.created_at > '2023-01-01' 
+AND o.status = 'COMPLETED';
+
+-- Хорошо: оптимизированный запрос
+SELECT u.id, u.name, u.email, COUNT(o.id) as order_count
+FROM users u 
+JOIN orders o ON u.id = o.user_id 
+WHERE u.created_at > '2023-01-01' 
+AND o.status = 'COMPLETED'
+GROUP BY u.id, u.name, u.email;
+
+-- Хорошо: использование индексов
+CREATE INDEX idx_user_created_at ON users(created_at);
+CREATE INDEX idx_order_status ON orders(status);
+CREATE INDEX idx_order_user_status ON orders(user_id, status);
+```
+
+### 2. Connection Pooling
+```java
+// Настройка пула соединений
+@Configuration
+public class DatabaseConfig {
+    @Bean
+    public DataSource dataSource() {
+        HikariConfig config = new HikariConfig();
+        config.setJdbcUrl("jdbc:postgresql://localhost:5432/mydb");
+        config.setUsername("user");
+        config.setPassword("password");
+        
+        // Оптимизация пула соединений
+        config.setMaximumPoolSize(20);
+        config.setMinimumIdle(5);
+        config.setConnectionTimeout(30000);
+        config.setIdleTimeout(600000);
+        config.setMaxLifetime(1800000);
+        config.setLeakDetectionThreshold(60000);
+        
+        return new HikariDataSource(config);
+    }
+}
+```
+
+### 3. Batch Operations
+```java
+// Batch операции
+@Repository
+public class OptimizedUserRepository {
+    @Autowired
+    private JdbcTemplate jdbcTemplate;
+    
+    // Batch вставка
+    public void saveUsers(List<User> users) {
+        String sql = "INSERT INTO users (name, email, created_at) VALUES (?, ?, ?)";
+        
+        jdbcTemplate.batchUpdate(sql, new BatchPreparedStatementSetter() {
+            @Override
+            public void setValues(PreparedStatement ps, int i) throws SQLException {
+                User user = users.get(i);
+                ps.setString(1, user.getName());
+                ps.setString(2, user.getEmail());
+                ps.setTimestamp(3, Timestamp.valueOf(user.getCreatedAt()));
+            }
+            
+            @Override
+            public int getBatchSize() {
+                return users.size();
+            }
+        });
+    }
+    
+    // Batch обновление
+    public void updateUsers(List<User> users) {
+        String sql = "UPDATE users SET name = ?, email = ? WHERE id = ?";
+        
+        jdbcTemplate.batchUpdate(sql, new BatchPreparedStatementSetter() {
+            @Override
+            public void setValues(PreparedStatement ps, int i) throws SQLException {
+                User user = users.get(i);
+                ps.setString(1, user.getName());
+                ps.setString(2, user.getEmail());
+                ps.setLong(3, user.getId());
+            }
+            
+            @Override
+            public int getBatchSize() {
+                return users.size();
+            }
+        });
+    }
+}
+```
+
+## Настройка базы данных
+
+### 1. Index Optimization
+```sql
+-- Оптимизация индексов
+-- Анализ использования индексов
+EXPLAIN ANALYZE SELECT * FROM users WHERE email = 'user@example.com';
+
+-- Создание составных индексов
+CREATE INDEX idx_user_email_status ON users(email, status);
+
+-- Создание частичных индексов
+CREATE INDEX idx_active_users ON users(email) WHERE status = 'ACTIVE';
+
+-- Создание функциональных индексов
+CREATE INDEX idx_user_lower_email ON users(LOWER(email));
+```
+
+### 2. Query Plan Analysis
+```sql
+-- Анализ планов выполнения
+EXPLAIN (ANALYZE, BUFFERS) 
+SELECT u.name, COUNT(o.id) as order_count
+FROM users u 
+LEFT JOIN orders o ON u.id = o.user_id 
+WHERE u.created_at > '2023-01-01'
+GROUP BY u.id, u.name;
+
+-- Анализ статистики
+ANALYZE users;
+ANALYZE orders;
+
+-- Обновление статистики
+UPDATE pg_stat_user_tables 
+SET n_tup_ins = 0, n_tup_upd = 0, n_tup_del = 0 
+WHERE relname = 'users';
+```