// Room (Android) — локальное хранилище
@Entity(tableName = "orders")
data class Order(
    @PrimaryKey val id: String,
    val address: String,
    val status: String,
    val synced: Boolean = false
)

@Dao
interface OrderDao {
    @Insert
    suspend fun insert(order: Order)

    @Query("SELECT * FROM orders WHERE synced = 0")
    suspend fun getUnsyncedOrders(): List<Order>

    @Update
    suspend fun update(order: Order)
}

// Менеджер синхронизации
class SyncManager(private val dao: OrderDao, private val api: ApiService) {
    suspend fun sync() {
        val unsynced = dao.getUnsyncedOrders()
        unsynced.forEach { order ->
            try {
                api.sendOrder(order)
                dao.update(order.copy(synced = true))
            } catch (e: Exception) {
                // Оставляем synced = false для следующей попытки
            }
        }
    }
}

import time
from threading import Lock

class CircuitBreaker:
    def __init__(self, failure_threshold=5, timeout=30):
        self.failure_threshold = failure_threshold
        self.timeout = timeout
        self.failures = 0
        self.last_failure_time = 0
        self.state = "CLOSED"  # CLOSED, OPEN, HALF_OPEN
        self.lock = Lock()

    def call(self, func, fallback):
        with self.lock:
            if self.state == "OPEN":
                if time.time() - self.last_failure_time > self.timeout:
                    self.state = "HALF_OPEN"
                else:
                    return fallback()

        try:
            result = func()
            if self.state == "HALF_OPEN":
                self.state = "CLOSED"
                self.failures = 0
            return result
        except Exception:
            with self.lock:
                self.failures += 1
                self.last_failure_time = time.time()
                if self.failures >= self.failure_threshold:
                    self.state = "OPEN"
            return fallback()

# Использование
cb = CircuitBreaker(failure_threshold=3, timeout=15)

def risky_payment():
    # вызов внешнего API
    response = requests.post("https://payment-gateway/pay", timeout=5)
    response.raise_for_status()
    return response.json()

def fallback_payment():
    return {"status": "pending", "message": "Сервис временно недоступен, повторите позже"}

result = cb.call(risky_payment, fallback_payment)

import time
from threading import Lock

class CircuitBreaker:
    def __init__(self, failure_threshold=5, timeout=30):
        self.failure_threshold = failure_threshold
        self.timeout = timeout
        self.failures = 0
        self.last_failure_time = 0
        self.state = "CLOSED"  # CLOSED, OPEN, HALF_OPEN
        self.lock = Lock()

    def call(self, func, fallback):
        with self.lock:
            if self.state == "OPEN":
                if time.time() - self.last_failure_time > self.timeout:
                    self.state = "HALF_OPEN"
                else:
                    return fallback()

        try:
            result = func()
            if self.state == "HALF_OPEN":
                self.state = "CLOSED"
                self.failures = 0
            return result
        except Exception:
            with self.lock:
                self.failures += 1
                self.last_failure_time = time.time()
                if self.failures >= self.failure_threshold:
                    self.state = "OPEN"
            return fallback()

# Использование
cb = CircuitBreaker(failure_threshold=3, timeout=15)

def risky_payment():
    # вызов внешнего API
    response = requests.post("https://payment-gateway/pay", timeout=5)
    response.raise_for_status()
    return response.json()

def fallback_payment():
    return {"status": "pending", "message": "Сервис временно недоступен, повторите позже"}

result = cb.call(risky_payment, fallback_payment)

Это хороший знак: рынок перестаёт довольствоваться «человеком‑исполнителем» и всё больше ценит тех, кто понимает, зачем нужен каждый документ, схема и требование, и как всё это связано в одну систему.

CREATE TABLE product_attributes (
    product_id INT,
    attr_name VARCHAR(50),
    attr_value VARCHAR(255)
);

// Документ товара
{
    "_id": 123,
    "name": "iPhone 15",
    "price": 799,
    "attributes": {
        "screen": "6.1 inch",
        "storage": "128 GB",
        "camera": "48 MP"
    }
}

-- Создаём партиционированную таблицу
CREATE TABLE events (
    id SERIAL,
    user_id INT,
    event_time TIMESTAMP,
    payload JSONB
) PARTITION BY RANGE (event_time);

-- Удаление партиций старше 30 дней (процедура)
CREATE OR REPLACE FUNCTION drop_old_partitions()
RETURNS void AS $$
DECLARE
    partition_name TEXT;
BEGIN
    FOR partition_name IN
        SELECT tablename FROM pg_tables
        WHERE tablename LIKE 'events_%'
        AND tablename < 'events_' || TO_CHAR(NOW() - INTERVAL '30 days', 'YYYY_MM_DD')
    LOOP
        EXECUTE 'DROP TABLE ' || partition_name;
    END LOOP;
END;
$$ LANGUAGE plpgsql;