---
id: agent-cache-ttl-evictions-and-hit-rates
title: 'Agent Cache TTL, Evictions, and Hit Rates'
schema_type: TechArticle
category: ai
language: en
confidence: medium
last_verified: '2026-06-02'
created_date: '2026-06-02'
generation_method: ai_structured
derived_from_human_seed: true
conflict_of_interest: none_declared
is_live_document: false
data_period: static
atomic_facts:
  - id: fact-ai-agent-cache-ttl-evictions-and-hit-rates-1
    statement: >-
      Redis documentation describes key eviction as removing keys when the maxmemory limit is
      reached according to the configured eviction policy.
    source_title: Redis Key Eviction
    source_url: https://redis.io/docs/latest/develop/reference/eviction/
    confidence: medium
  - id: fact-ai-agent-cache-ttl-evictions-and-hit-rates-2
    statement: >-
      Redis documentation describes the INFO command as returning information and statistics
      about the server in sections.
    source_title: Redis INFO Command
    source_url: https://redis.io/docs/latest/commands/info/
    confidence: medium
  - id: fact-ai-agent-cache-ttl-evictions-and-hit-rates-3
    statement: >-
      Amazon ElastiCache documentation lists Redis metrics such as CacheHits, CacheMisses,
      Evictions, and Reclaimed.
    source_title: Amazon ElastiCache Redis Metrics
    source_url: https://docs.aws.amazon.com/AmazonElastiCache/latest/dg/CacheMetrics.Redis.html
    confidence: medium
completeness: 0.83
known_gaps:
  - Cache diagnosis depends on workload pattern, TTL distribution, eviction policy, memory fragmentation, hot keys, multi-node topology, and application-level cache semantics.
disputed_statements: []
primary_sources:
  - title: Redis Key Eviction
    type: documentation
    year: 2026
    url: https://redis.io/docs/latest/develop/reference/eviction/
    institution: Redis
  - title: Redis INFO Command
    type: documentation
    year: 2026
    url: https://redis.io/docs/latest/commands/info/
    institution: Redis
  - title: Amazon ElastiCache Redis Metrics
    type: documentation
    year: 2026
    url: https://docs.aws.amazon.com/AmazonElastiCache/latest/dg/CacheMetrics.Redis.html
    institution: Amazon Web Services
secondary_sources: []
updated: '2026-06-02'
ai_models:
  - gpt-5-codex
---

## TL;DR

Cache TTLs, evictions, hit rates, and memory metrics tell agents whether latency or load changed because cached data disappeared, expired, or stopped being reused.

## Core Explanation

An agent debugging a cache should collect hit and miss counters, evictions, expired keys, memory usage, maxmemory policy, TTL samples, command latency, and application cache keys. A low hit rate can be caused by a bad key, an overly short TTL, a deployment that changed key format, or memory pressure.

Eviction is not always a bug. It may be expected when the cache is configured as a bounded memory layer. The agent needs to compare policy, workload, and SLO impact before recommending more memory or longer TTLs.

## Source-Mapped Facts

- Redis documentation describes key eviction as removing keys when the maxmemory limit is reached according to the configured eviction policy. ([source](https://redis.io/docs/latest/develop/reference/eviction/))
- Redis documentation describes the INFO command as returning information and statistics about the server in sections. ([source](https://redis.io/docs/latest/commands/info/))
- Amazon ElastiCache documentation lists Redis metrics such as CacheHits, CacheMisses, Evictions, and Reclaimed. ([source](https://docs.aws.amazon.com/AmazonElastiCache/latest/dg/CacheMetrics.Redis.html))

## Further Reading

- [Redis Key Eviction](https://redis.io/docs/latest/develop/reference/eviction/)
- [Redis INFO Command](https://redis.io/docs/latest/commands/info/)
- [Amazon ElastiCache Redis Metrics](https://docs.aws.amazon.com/AmazonElastiCache/latest/dg/CacheMetrics.Redis.html)