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The article shows how using Collectors.toMap can trigger IllegalStateException for duplicate keys and NullPointerException for null values, and demonstrates proper merge functions, Optional handling, and a plain‑for‑loop alternative to safely convert a List of objects into a Map.
This article walks through setting up MinIO, installing it via Docker on CentOS 7, configuring Spring Boot, and implementing chunked, instant‑resume, and resumable uploads for large files, complete with code examples, Docker commands, and troubleshooting tips.
This article explains the fundamental concepts of service registries, examines CAP theory and consensus protocols, and provides a detailed analysis of Zookeeper, Eureka, Nacos, Consul, and Etcd—including their architectures, features, trade‑offs, and practical guidance for selecting the most suitable registry for a given environment.
This article walks through a complete gray‑release solution built on Spring Cloud, Nacos as the service registry, and a custom load‑balancer, detailing the architecture, code implementation, configuration, and step‑by‑step deployment to demonstrate traffic splitting and version routing.
This article presents ten essential advanced MySQL concepts—including CTEs, recursive CTEs, temporary functions, CASE‑WHEN pivots, EXCEPT vs NOT IN, self‑joins, ranking window functions, delta calculations, running totals, and date‑time manipulation—each explained with clear examples and practical SQL snippets.
The article walks through real interview scenarios where MySQL or Java processes consume 900% CPU, detailing step‑by‑step diagnosis with top, processlist, jstack, and concrete remediation such as adding indexes, using caches, fixing busy loops, and tuning memory.
The article explains why API debounce is essential, identifies the types of endpoints that need it, and walks through two SpringBoot solutions—Redis‑based shared cache and Redisson distributed lock—complete with custom annotations, key generation, code samples, test results, and practical limitations.
This article explains how to use Redis sorted sets (ZSET) together with user token or browser fingerprint identification to add, query, and clean online user entries, providing a simple yet effective method for counting active users in real time.
This article explains how InnoDB full‑text search can replace LIKE% fuzzy queries by using inverted indexes, covering index structures, creation syntax, MATCH() AGAINST() modes, practical demos, query expansion, and index removal, while noting when to prefer external search engines.
This article walks through Redis's architectural journey—from a lone instance to a high‑availability, high‑performance cluster—covering persistence (RDB, AOF, hybrid), master‑slave replication, Sentinel automatic failover, sharding strategies, and the modern Redis Cluster design.
