How to Store Billions of Webhook Audit Logs in PostgreSQL at Scale

A production engineering guide outlines strategies for managing billions of webhook audit records in PostgreSQL using time-based declarative partitioning and tools like pg_partman and pg_cron. The guide explains why a single large table eventually breaks down due to index bloat, cache churn, and costly row deletions as data volumes grow. Key techniques covered include targeted indexing, LZ4 TOAST payload compression, and partition-level data retention to keep storage efficient. The recommendations are verified against PostgreSQL 18, pg_partman 5.5.0, and pg_cron documentation as of late September 2026. A production checklist is provided, emphasizing that every application query must filter on created_at and that exports should be verified before any partition is dropped.