53e0065e3e
配置 SSOT（TOML + .env） 统一错误契约 Auth 与事务边界 Redis / Celery 可靠性:业务 Redis（DB/0）与 Celery broker/backend（DB/1）显式拆分；连接池、sync client 可观测性（OpenTelemetry + LGTM）
56 lines
1.4 KiB
Markdown
56 lines
1.4 KiB
Markdown
---
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title: Use Read Replicas for Read-Heavy Workloads
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impact: MEDIUM
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impactDescription: Scales read throughput without adding primary nodes
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tags: cluster, replicas, read-scaling, high-availability
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description: Use Read Replicas for Read-Heavy Workloads
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alwaysApply: true
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---
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## Use Read Replicas for Read-Heavy Workloads
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For read-heavy workloads, distribute reads across replicas to reduce load on primaries.
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**Correct:** Configure replica reads in Redis Cluster.
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```python
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from redis.cluster import RedisCluster
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rc = RedisCluster(
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host='localhost',
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port=6379,
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read_from_replicas=True # Distribute reads to replicas
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)
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# Writes go to primary
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rc.set("key", "value")
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# Reads can be served by replicas (eventually consistent)
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value = rc.get("key")
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```
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**Correct:** Use replica reads in standalone replication setup.
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```python
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from redis import Redis
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# Connect to primary for writes
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primary = Redis(host='primary-host', port=6379)
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# Connect to replica for reads
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replica = Redis(host='replica-host', port=6379)
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# Write to primary
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primary.set("key", "value")
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# Read from replica (eventually consistent)
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value = replica.get("key")
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```
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**Considerations:**
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- Replica reads are eventually consistent
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- Don't read from replicas for data that was just written
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- Use for read-heavy, slightly-stale-OK workloads (caches, analytics, dashboards)
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Reference: [Redis Replication](https://redis.io/docs/latest/operate/oss_and_stack/management/replication/)
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