dimgigov
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Documentation updates: - Fix v0.1.0 → v1.1.0 version numbers in en, ru, fa, zh docs - Add missing Window Functions, Multi-Tenant ERP, Supported Keywords sections to ru, fa, zh baraql.md (~105 lines each) - Expand Turkish and Arabic baraql.md (110 → 268 lines) - Expand Turkish and Arabic installation.md (62 → 307 lines) - Add new Bulgarian documentation files (18 new files) Client updates: - Python: Full async/await rewrite with asyncio, request queueing - Rust: Full async/await rewrite with tokio, async examples - Nim: Update README to v1.1.0 - All clients now support async patterns consistently
2.1 KiB
2.1 KiB
Транзакции и MVCC
MVCC (Multi-Version Concurrency Control) със snapshot изолация и deadlock детекция.
Употреба
import barabadb/core/mvcc
var tm = newTxnManager()
let txn = tm.beginTxn()
# Операции за запис
discard tm.write(txn, "key1", cast[seq[byte]]("value1"))
discard tm.write(txn, "key2", cast[seq[byte]]("value2"))
# Savepoint
tm.savepoint(txn)
discard tm.write(txn, "key3", cast[seq[byte]]("value3"))
discard tm.rollbackToSavepoint(txn) # отмяна на key3
# Commit
discard tm.commit(txn)
Изолация на Транзакции
BaraDB използва snapshot изолация:
- Четящите не блокират пишещите
- Пишещите не блокират четящите
- Всяка транзакция вижда консистентен snapshot
Deadlock Детекция
import barabadb/core/deadlock
var detector = newDeadlockDetector()
if detector.detectCycle(txn1, txn2):
echo "Открит deadlock!"
Write-Ahead Log
import barabadb/storage/wal
var wal = newWAL("./wal")
wal.append(txnId, "SET key value")
wal.flush()
Savepoints
Вложени savepoints на транзакции:
tm.savepoint(txn, "sp1")
# ... операции ...
tm.rollbackToSavepoint(txn, "sp1")
Формална Верификация
MVCC / Snapshot Isolation протоколът е формално специфициран в TLA+:
- Спецификация:
formal-verification/mvcc.tla - Проверени свойства:
NoDirtyReads— транзакциите никога не четат некомитнати данниReadOwnWrites— транзакциите винаги виждат собствените си записиWriteWriteConflict— first-committer-wins (няма две комитнати транзакции да пишат един и същ ключ)
Пускане на TLC локално:
cd formal-verification
java -cp tla2tools.jar tlc2.TLC -config models/mvcc.cfg mvcc.tla