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Databases

Redis & Caching

Eviction, persistence, memory limits and cache invalidation gone wrong.

4 articles

Databases10 min read

Your Redis Cache Is Serving Yesterday's Data: Fixing Invalidation Properly

Stale cache incidents have no error message, only a DEL that returns 0. Here is why Redis invalidation breaks, the structural fix, and how to prove it worked.

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Payments & Fintech9 min read

Daraja 404.001.03: Cache the Access Token, Don't Mint a New One

M-Pesa Daraja tokens live about an hour. Fetching one per request gets you throttled; caching forever gets you 404.001.03. The proactive refresh pattern Safaricom never documents.

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Databases7 min read

Redis 'OOM command not allowed': Why Switching to LRU Can Cost You Data

The one-line fix for Redis OOM errors quietly deletes your data. Here is how to tell a safe cache instance from a durable one, and what to set for each.

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Frappe/ERPNext7 min read

Redis 'Connection refused' in Frappe: Find the Real Cause, Not Just Restart

Error 111 connecting to localhost:13000 is not a wrong port, it means nothing is listening. Read the real port, ping it, then fix the actual cause per deployment type.

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