Apa itu Redis Streams?

Question

Accepted Answer

**Redis Streams** minangka struktur data log append-only — kaya durable message queue utawa event log — ndhukung **consumer groups**, message persistence, acknowledgments, lan replay. Iki minangka jawaban Redis kanggo reliable messaging, luwih robust tinimbang Pub/Sub (kang fire-and-forget).

## Log append-only saka messages

```bash
# add entries to a stream (each gets an auto ID: timestamp-sequence)
XADD events * type "signup" user "ann"     # * = auto-generate ID; returns e.g. 1700000000-0
XADD events * type "login" user "bob"

XLEN events                                 # number of entries
XRANGE events - +                           # read all entries (- to +)
XREAD COUNT 10 STREAMS events 0             # read entries (from ID 0)
```

Streams minangka **log append-only**: entries ditambahake karo `XADD` (saben siji duwe unique, time-ordered ID) lan tahan ing stream — ora kaya Pub/Sub, messages ora ilang; iku disimpen lan bisa diwaca maneh.

## Consumer groups — reliable, scalable processing

```bash
# create a consumer group to process the stream
XGROUP CREATE events workers 0

# consumers read messages (each message goes to ONE consumer in the group)
XREADGROUP GROUP workers consumer1 COUNT 1 STREAMS events >

# acknowledge a processed message (so it's not redelivered)
XACK events workers 1700000000-0
# unacknowledged messages can be reclaimed (XPENDING/XCLAIM) → no message lost on crash
```

**Consumer groups** nyebarake messages menyang akeh consumers (scaling processing), karo saben message menyang siji consumer, **acknowledgments** (`XACK`) ngukuhake processing, lan **pending/reclaim** (`XPENDING`/`XCLAIM`) nyiyakake messages ora ilang yen consumer ambruk — reliable, at-least-once delivery.

## Streams vs Pub/Sub

```text
PUB/SUB  → fire-and-forget; offline subscribers MISS messages; no persistence/replay
STREAMS  → PERSISTENT log; messages stored; consumer groups; acknowledgments; replay
  → Streams = when you need RELIABLE delivery, message history, and scalable consumers
  → Pub/Sub = simple real-time broadcast where missing messages is OK
Streams are similar to a lightweight Kafka (log + consumer groups).
```

## Mulane iku penting

Paham Redis Streams penting kanggo **reliable messaging lan event processing** ing Redis, dadi pengetahuan berguna — utamane amarga Streams ngatasi keterbatasan utama Pub/Sub.

Kadhangkala Pub/Sub iku simple nanging fire-and-forget (offline subscribers selamane ilang messages, ora ana persistence), **Streams nyedhiyake reliable messaging**: **log persistent append-only** kang messages disimpen (ora ilang) lan bisa diwaca/diputar maneh, plus **consumer groups** kang nyebarake messages menyang akeh consumers kanggo scalable processing, **acknowledgments** (`XACK`) kanggo ngukuhake processing, lan **pending-message reclaim** (`XPENDING`/`XCLAIM`) dadi messages ora ilang nalika consumer ambruk — ngadhelake at-least-once, reliable, scalable message processing.

Paham **Streams vs Pub/Sub** (Streams kanggo reliable delivery, history, lan scalable consumers; Pub/Sub kanggo simple real-time broadcast kang ilang bisa ditarima) penting kanggo milih Redis messaging primitive kang tepat.

Ngenali yen Streams **padha karo lightweight Kafka** (log-based karo consumer groups) mbantu frame peran — nyedhiyake event-streaming/message-queue capabilities ing Redis tanpa separate broker kanggo kebutuhan sedeng, dene dedicated brokers (Kafka, RabbitMQ) tetep pas kanggo messaging luwih gedhe utawa lebih demanding.

Sajrone reliable messaging lan event processing minangka kebutuhan umum, lan sejak Redis Streams nyedhiyake solusi robust, persistent, consumer-group-based (ngatasi keterbatasan fire-and-forget Pub/Sub) ing Redis, paham Redis Streams — log append-only, consumer groups karo acknowledgments lan reclaim, lan cara iku dibanding Pub/Sub lan Kafka — minangka pengetahuan penting, praktis-relevan kanggo ngebang reliable messaging lan event-driven features karo Redis, pilihan tepat nalika butuh delivery guarantees lan message history kang Pub/Sub ora bisa nyedhiyake.