Audit and Compliance Platform

Summary

An append-only audit log architecture for capturing system actions: user operations, data access events, configuration changes, and financial operations: with cryptographic integrity chaining, immutable storage, and dual-path query serving. PostgreSQL stores the authoritative append-only event log in time-partitioned tables; ClickHouse serves historical aggregate queries and retention analytics; Kafka streams audit events in real time to SIEM integrations and security dashboards; Redis caches hot audit query results for compliance-facing read paths. No record is ever updated or deleted: only inserts are permitted. Each record includes a hash of the previous record, forming a tamper-evident chain verifiable without external tooling.

Problem Statement

Compliance and security audit systems must balance three competing constraints: high ingestion throughput (every application action generates an audit record), long retention with range query performance (compliance queries span months or years), and tamper evidence (every record must be verifiable as unmodified after write). Traditional mutable databases expose all three failure points: records can be deleted, queries degrade with table size, and there is no structural mechanism to detect after-the-fact modification. The write path must handle bursts of concurrent audit events without contention; the read path must serve time-range and actor-scoped queries across hundreds of millions of records without full-table scans; and the integrity chain must be maintained without becoming a write serialization bottleneck.