Tag: Redis

1. Pub/Sub for Real-Time Events Between Services

   Jul 24, 2025

   Redis Pub/Sub distributes messages in real time to all currently connected subscribers, without storing them or giving any delivery guarantee. This fire-and-forget semantic makes Pub/Sub ideal for live notifications between services, but unsuitable for anything that needs persistence or guaranteed delivery.

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2. Backup and Restore Strategies for Production Redis Instances

   Jun 29, 2025

   Persistence mechanisms like RDB and AOF protect against a process crash, but not against a failed disk, a deleted server, or a human mistake. A solid backup strategy for Redis copies snapshots consistently, automates retention, regularly tests restores, and keeps at least one copy outside the production infrastructure.

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3. Redis HyperLogLog for Approximate Counting

   May 18, 2025

   Count millions of unique visitors without storing millions of individual IDs: HyperLogLog estimates the cardinality of a set with a fixed memory footprint of only 12 kilobytes and a typical error of about 0.81 percent, regardless of whether the set contains a thousand or a billion elements.

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4. Redis Security Hardening for Production

   May 11, 2025

   Redis is configured by default for maximum performance, not maximum security. Without authentication, with an open network bind and dangerous commands enabled, a production Redis instance becomes an easy target. This article shows the complete hardening process for Magento environments, from passwords and ACLs to TLS.

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5. Redis vs. Varnish: Clear Roles in Magento

   May 9, 2025

   Redis and Varnish are often pitted against each other in Magento discussions, yet they solve fundamentally different problems. Redis is the cache and session backend for object cache and full page cache storage, Varnish is the HTTP layer in front that delivers whole pages before Magento even starts. This article explains the clean role split.

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6. Master-Replica Replication in Detail

   May 8, 2025

   Redis replication looks simple at first glance: one command, one connection, data flows from master to replica. Underneath, though, the PSYNC protocol decides whether a brief network interruption costs only a few kilobytes or requires retransferring the entire dataset, and an incorrectly sized backlog regularly wipes out exactly that advantage in practice.

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7. Session Backend Tuning for Magento with Redis

   Apr 30, 2025

   A misconfigured session backend is one of the most common yet hardest to diagnose causes of slow Magento shops. Session locking, timeout values and the break_after_frontend parameter decide whether parallel Ajax requests within a session block each other or run cleanly side by side. This article shows step by step how to correctly configure the Redis session backend.

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8. Data Loss Scenarios in Redis and How to Guard Against Them

   Apr 28, 2025

   Data loss in Redis rarely comes from a single obvious mistake, but from the interplay of fsync timing, replication lag and automatic failover under time pressure. Knowing the concrete scenarios under which Redis actually loses data lets you deliberately combine the right safeguards, instead of relying on a single feature.

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9. Redis Troubleshooting: Common Errors in Magento Environments

   Apr 7, 2025

   When Redis causes trouble in a Magento environment, only a handful of error patterns are really common: refused connections, OOM errors on writes, and session lock timeouts during checkout. This article walks through each of these error patterns systematically, showing the diagnostic steps and the concrete fix.

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10. Preventing Cache Stampede: Locking and Probabilistic Refresh

    Apr 6, 2025

    When a heavily requested Redis key expires, hundreds of concurrent requests often hit the database unchecked, because each request handles the cache miss independently. This phenomenon is called cache stampede or thundering herd and can be prevented deliberately with mutex locking or probabilistic early expiration, without giving up the benefits of the cache.

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