Author: Rahul Mittal

Introduction A Java application that works in development may fail in production because of: Missing indexes Poor schema design Connection pool exhaustion Large transactions N+1 queries Missing pagination Unoptimized SQL…

Introduction In enterprise applications, data correctness is more important than performance. Consider these situations: Two users update the same order. Multiple payment requests arrive simultaneously. Inventory quantity is updated concurrently.…

Introduction Most JPA applications work perfectly during development. Problems begin in production: Pages become slow. APIs execute hundreds of SQL statements. CPU usage increases. Database load increases. Memory usage grows.…

Introduction Primary key design is one of the most important decisions in database design. A poorly chosen key can cause: ❌ Complex joins ❌ Difficult JPA mappings ❌ Large indexes…

Introduction Relationships are the foundation of every enterprise application. Consider these examples: Customer → Orders Order → Order Items Employee → Department User → Roles Student → Courses In relational…

Introduction Most modern Java applications do not directly use JDBC. Instead, they use an Object Relational Mapping (ORM) framework such as Hibernate through the Java Persistence API (JPA). JPA solves…

Introduction Every Java application eventually talks to a database. Before JPA, Hibernate, and Spring Data existed, Java applications used JDBC directly. Even today, every ORM framework ultimately uses JDBC underneath.…

Introduction Most Java performance problems eventually become SQL problems. Applications become slow because of: Missing indexes Poor joins Full table scans Excessive sorting Improper pagination Incorrect SQL design Large result…