🧩 TL;DR: A subtle expireAfterAccess bug in a dual-cache setup caused thousands of evictions in a small cache — even for reused keys. The root cause? Only one side of the bidirectional cache was touched on read, leading to silent expiry in the reverse map. This engineering postmortem breaks down how different experience levels (from …
📘 @PolicyScope Annotation System This document explains how to define, use, and enforce repeatable @PolicyScope annotations in a Spring Boot application using Aspect-Oriented Programming (AOP). 🧩 Purpose @PolicyScope is a repeatable annotation used to declare one or more logical access scopes on a method. These scopes can be inspected at runtime to enforce access control …
✅ System Architecture Summary Layer Timezone Setting Purpose JVM (Java) Asia/Kolkata (+05:30) Governs now() calls and default serialization of time values JDBC / Hibernate UTC Ensures consistent, zone-neutral storage and retrieval in the database PostgreSQL Server America/Denver Controls how TIMESTAMPTZ values are interpreted/displayed in SQL tools API Output Asia/Kolkata JVM re-applies India zone on deserialization …
This document introduces the Unicode character set — what it is, why it exists, and how it’s encoded using formats such as UTF-8 and UTF-16. It concludes with an overview of how Java internally represents Unicode. 🔤 1. What Is Unicode? Unicode is a universal character set standard designed to consistently represent text from every …
🕒 Java Developer’s Guide to Understanding Time This comprehensive guide explains how Java developers should think about time, timezones, DST (Daylight Saving Time), and formats like ISO 8601 and RFC 3339. It makes an explicit and critical distinction between the representation of time (format) and the interpretation of time (timezone). Most importantly, it clarifies a …
✅ TL;DR ChronoGraf is a high-performance, Java-based time series analytics platform backed by PostgreSQL.It supports three complementary data modes: Each is available across six fixed UTC-aligned temporal granularities:5s, 1m, 1h, 1d, 1w, 1mo. With mixed-granularity querying, dynamic percentile calculation, and late event correction (via upward propagation), ChronoGraf provides scalable, accurate analytics for: It runs as …
Overview A comprehensive time series service designed to handle multiple data types and query patterns for event-driven applications. The service supports both aggregated metrics (counting and histograms) and detailed event retrieval with flexible filtering capabilities. Core Functionality Data Types Supported The service handles two primary data categories: Key Features Metrics Storage and Retrieval The service …
Executive Summary This document describes an optimized approach for retrieving histogram data stored across multiple temporal granularities (5-second, 1-minute, 1-hour, 1-day, 1-week, 1-month) when querying with timezone-specific ranges. The solution leverages histogram aggregation properties to minimize data retrieval overhead while maintaining statistical accuracy through intelligent granularity selection and bucket merging. Problem Statement Histogram data is …
Executive Summary This document describes an optimized approach for retrieving time series event counter data stored in multiple granularities (5-second, 1-minute, 1-hour, 1-day, 1-week, 1-month) when querying with timezone-specific ranges. The solution minimizes data retrieval overhead while ensuring precise boundary coverage through intelligent granularity selection. Problem Statement Time series data is stored in UTC-aligned segments …
In the annals of aviation, there are few aircraft that have inspired awe quite like the Airbus A380. Colossal, graceful, and whisper-quiet, the double-decked superjumbo was more than just a plane. It was a flying cathedral of engineering brilliance and a symbol of humanity’s unrelenting ambition to reach higher, farther, and in greater comfort than …