Redis transactions (melalui MULTI/EXEC) nglumpukake akeh perintah kanggo nglaksanake atomically — kabeh bersamaan tanpa perintah liyane nyisip. Digabung karo WATCH kanggo optimistic locking, dheweke nangani skenario sing butuh akeh operasi kanggo konsisten. Redis transactions beda saka SQL transactions kanthi cara penting.
MULTI # start a transaction (begin queuing commands)
SET account:1 100 # QUEUED (not executed yet)
SET account:2 200 # QUEUED
INCR counter # QUEUED
EXEC # execute ALL queued commands atomically (as one unit)
# → all commands run together, with NO other client's commands in between
MULTI miwiti antriing perintah; EXEC njalanake kabeh atomically (ora ana nyisip saka klien liyane). DISCARD mbatalake transaksi sing antri.
# WATCH a key; if it CHANGES before EXEC, the transaction ABORTS (returns nil)
WATCH balance
val = GET balance # read the current value
MULTI
SET balance (val - 100) # modify based on what we read
EXEC # → if "balance" changed since WATCH, EXEC fails (returns nil)
# → retry the whole thing if it failed (optimistic concurrency control)
WATCH nyediake optimistic locking: yen kunci sing dipantau diowah dening klien liyane sadurunge EXEC, transaksi batal — ngidini sampeyan kanthi aman nggawe operasi check-then-set (coba maneh nalika ana konflik).
⚠️ Redis transactions are NOT like SQL transactions:
✗ NO ROLLBACK — if a command fails at EXEC time, OTHER commands still execute
(errors don't roll back the transaction; Redis doesn't undo). Only syntax errors
before EXEC abort the whole thing.
✓ Atomicity = commands run together without interleaving (isolation), NOT all-or-nothing
with rollback on error.
→ Often Lua SCRIPTS are used instead for complex atomic logic (a script runs atomically).
Paham Redis transactions punika migunani kanggo nindakake akeh operasi kanthi konsisten, mula iku migunani kawruh — lan paham kepiye dheweke beda saka SQL transactions utamane penting kanggo nyegah asumsi sing salah.
Kapabilitas inti — MULTI/EXEC nglumpukake perintah kanggo nglaksanake atomically (kabeh bersamaan, tanpa perintah saka klien liyane nyisip) — nangani skenario mana akeh operasi kudu dadi unit konsisten.
Mekanisme WATCH nyediake optimistic locking (check-and-set): mbatalake transaksi yen kunci sing dipantau ganti sadurunge EXEC, ngidini operasi check-then-modify sing aman (kaya ngurangi saldo miturut nilai samenika) karo coba maneh nalika konflik — penting kanggo operasi concurrent sing bener.
Poin paling kritis yaiku paham kepiye Redis transactions BEDA saka SQL transactions: Redis ora duwe rollback — yen perintah gagal ing wektu EXEC, perintah liyane tetep nglaksanake (Redis ora ngebali), mula "atomicity" ing kene tegese perintah nglaksanake bersamaan tanpa nyisip (isolation), DUDU kabeh-utawa-apa-apa karo rollback kesalahan.
Mispaham iki (ngira rollback kaya SQL) gawe error handling sing salah.
Kawruh yen Lua scripts asring digunakake sebagai ganti kanggo logika atomik kompleks (script nglaksanake atomically minangka unit) iku migunani.
Amarga consistent multi-operation execution lan concurrent correct punika kabutuhan nyata, lan amarga Redis transactions (MULTI/EXEC karo WATCH kanggo optimistic locking) nangani dheweke nanging karo perbedaan penting saka SQL (ora duwe rollback) sing kudu dimangerteni, paham Redis transactions — MULTI/EXEC, WATCH-based optimistic locking, lan utamane distinsi ora-rollback saka SQL — iku migunani, kawruh praktis-relevan kanggo nggunakake Redis kanthi bener ing skenario concurrent, mana paham perbedaane saka SQL transactions sing biasane gunggung iku penting kayak mekanisme dhewe.