• Ошибка: ERROR: could not serialize access due to concurrent update (SQLSTATE 40001).
• Откат транзакций при параллельной записи в одни и те же строки/таблицы.
• Сбои проведения документов в 1С при управляемых блокировках.

1. Анализ конфликтующих параллельных транзакций

SELECT 
    blocked_locks.pid AS blocked_pid,
    blocking_locks.pid AS blocking_pid,
    blocked_activity.query AS blocked_statement,
    blocking_activity.query AS current_statement_in_blocking_process
FROM pg_catalog.pg_locks blocked_locks
JOIN pg_catalog.pg_stat_activity blocked_activity ON blocked_activity.pid = blocked_locks.pid
JOIN pg_catalog.pg_locks blocking_locks 
    ON blocking_locks.locktype = blocked_locks.locktype
    AND blocking_locks.database IS NOT DISTINCT FROM blocked_locks.database
    AND blocking_locks.relation IS NOT DISTINCT FROM blocked_locks.relation
    AND blocking_locks.page IS NOT DISTINCT FROM blocked_locks.page
    AND blocking_locks.tuple IS NOT DISTINCT FROM blocked_locks.tuple
    AND blocking_locks.virtualxid IS NOT DISTINCT FROM blocked_locks.virtualxid
    AND blocking_locks.transactionid IS NOT DISTINCT FROM blocked_locks.transactionid
    AND blocking_locks.classid IS NOT DISTINCT FROM blocked_locks.classid
    AND blocking_locks.objid IS NOT DISTINCT FROM blocked_locks.objid
    AND blocking_locks.objsubid IS NOT DISTINCT FROM blocked_locks.objsubid
    AND blocking_locks.pid != blocked_locks.pid
JOIN pg_catalog.pg_stat_activity blocking_activity ON blocking_activity.pid = blocking_locks.pid
WHERE NOT blocked_locks.granted;

2. Реализация механизма Retry (Повтора транзакций)

Архитектура MVCC на уровнях REPEATABLE READ и SERIALIZABLE требует обязательной обработки ошибки 40001 на уровне клиента с повторным запуском упавшей транзакции.

3. Оптимизация уровня изоляции по умолчанию

-- Проверка текущего уровня
SHOW default_transaction_isolation;
-- Установка стандартного Read Committed для снижения аномалий
ALTER SYSTEM SET default_transaction_isolation = 'read committed';
SELECT pg_reload_conf();

4. Уменьшение длительности блокирующих транзакций

Разбивайте массивные апдейты строк на пачки по 5000-10000 записей.