Memory Eviction Log

The unique key or identifier of the data item that was removed from the memory store. This is the primary lookup key used to reference the item.

• Examples: A session ID (session_abc123), a document UUID, a vector embedding ID, or a composite key like user:456:preferences.
• Purpose: Enables precise tracing of which specific piece of data was affected by the eviction policy.

The precise date and time (typically in UTC and ISO 8601 format) when the eviction operation was executed.

• Format: 2024-05-15T14:30:22.123Z
• Criticality: Essential for temporal analysis, correlating evictions with system load, and reconstructing the sequence of events during incident investigations.

The specific rule or condition that caused the item to be evicted. This documents the "why" behind the removal.

• Common Policies:
  • LRU (Least Recently Used): Item was the oldest accessed.
  • LFU (Least Frequently Used): Item had the lowest access count.
  • TTL Expiry (Time-To-Live): Item's predefined lifespan ended.
  • Capacity: Cache reached its maximum size limit.
  • Manual Invalidation: Explicitly deleted via an API call.

The quantitative value used by the eviction algorithm to make its decision. This provides insight into the item's state relative to the policy at the moment of eviction.

• LRU: Last access timestamp.
• LFU: Total access count.
• TTL: Remaining time until expiry at eviction (often 0).
• Size-Based: Size of the item in bytes.
• This data allows engineers to validate policy behavior and tune thresholds.

Identifies the specific logical or physical memory component from which the item was evicted. This is crucial in systems with layered or sharded memory architectures.

• Examples:
  • in_memory_lru_cache
  • redis_shard_3
  • vector_db_episodic_memory
  • level_2_disk_cache
• Use Case: Isolates performance or policy issues to a particular component of a distributed memory system.

A unique identifier (Correlation ID) linking this eviction to the broader request chain or agent session that may have triggered it. Often includes supplemental context.

• Correlation ID: A UUID propagated across all microservice logs for a single user request.
• Contextual Metadata: May include the agent ID, user ID, session ID, or the API operation (e.g., large_upload) that precipitated a capacity-driven eviction.
• Value: Enables end-to-end tracing to understand the systemic impact of a single eviction event.

The governing rule set that dictates how long data persists in a memory store before automated deletion or archival. This policy is the declarative source of truth that the eviction log records as being enforced.

• Examples: "Delete chat history after 30 days," "Archive task results after 1 year."
• Directly drives the logic captured in the Memory Eviction Log.

A comprehensive, immutable ledger of all access and modification events within a memory system. While an eviction log records deletions, an audit trail provides a full history for security and compliance.

• Includes: All reads, writes, updates, and deletions (evictions).
• Purpose: Forensic analysis, regulatory compliance (e.g., GDPR right to erasure), and debugging data lifecycle issues.

Quantitative measurements that track the operational performance and health of a memory system. Key metrics provide context for interpreting eviction log volume and patterns.

• Critical Metrics:
  • Cache Hit Rate: Percentage of reads served from cache. A low rate may trigger more aggressive eviction.
  • Memory Utilization: Percentage of allocated storage used. High utilization correlates with increased eviction activity.
  • Eviction Rate: The frequency of eviction events per second, directly measurable from the eviction log.

The time delay between a request to the memory system and its completion. Eviction policies are often tuned to optimize latency by keeping the most relevant data readily accessible.

• Impact of Eviction: Poorly tuned eviction can cause cache thrashing, where frequently needed data is constantly evicted and reloaded, drastically increasing read latency.
• The eviction log helps diagnose latency spikes by revealing periods of high churn.

A diagnostic API endpoint or procedure that verifies the memory system is operational and performing within expected parameters. It often checks the ability to write, read, and, implicitly, manage data lifecycle.

• Checks Performed: Connection to storage backend, responsiveness of core APIs, and verification that background processes (like eviction) are functioning.
• Anomalies in eviction log flow can trigger health check failures.