Formerly called 'Code to 35'. Add our main WeChat ID to access a wealth of shared resources (algorithms, interview prep, tech stacks: Java, Python, Go, big data). We mainly share serious development techniques, focusing on output-driven input. Occasionally we post life snippets and gossip. Our aim is to attract precise traffic and test advertising opportunities.
This article compiles a concise reference of fifty commonly used Linux commands, detailing each command’s purpose, typical usage syntax, concrete examples, and handy tips to help developers and system administrators quickly master essential command‑line operations.
This article explains how Java’s garbage collector interacts with the four reference types—Strong, Soft, Weak, and Phantom—detailing their behavior, typical use cases, and code examples that show when each reference allows an object to be reclaimed.
The article explains why MySQL 8 replaces fragmented, non‑transactional metadata files with a unified, InnoDB‑backed transactional data dictionary, details the information_schema views that expose it, and enumerates the resulting benefits such as atomicity, consistency, crash recovery, performance gains, simplified administration, reduced lock contention, smoother upgrades, improved DDL handling, and enhanced security.
This article explains Elasticsearch's post_filter mechanism, outlines scenarios where post‑query filtering is beneficial, provides DSL examples for filtering search hits and aggregations, and offers optimization tips to balance precision and query performance.
The article explains how Elasticsearch implements efficient search using an inverted index, detailing its components—posting list, term dictionary, and term index—illustrating the query flow with concrete examples, compression techniques, and the role of Lucene.
This article compiles twelve advanced Spring interview questions covering bean initialization and lifecycle, AOP implementation, transaction management, the differences between ApplicationContext and BeanFactory, type conversion mechanisms, dependency injection, circular dependency resolution with three‑level caches, the event system, @Transactional and @Async annotations, and the inner workings of DispatcherServlet.
The article systematically compares four major API styles—SOAP, REST, GraphQL, and RPC—detailing each one's core characteristics, advantages, limitations, and suitable use‑cases, and concludes with guidance on selecting the most appropriate protocol based on security, performance, complexity, and team expertise.
This article explains MD5’s history, the four‑step algorithm that produces a 128‑bit hash, common uses such as data integrity and password storage, the critical security flaws like collisions, and why modern systems should switch to stronger hashes like SHA‑256 or SHA‑3.
The article explains Elasticsearch’s internal Doc Values column‑store structure, why it outperforms the inverted index for sorting and aggregation, how it is generated, stored, compressed, and used in queries, and provides practical mapping examples.
RocksDB, an open‑source key‑value storage engine created by Facebook in 2012, delivers high performance, durability, and tunable configurations for flash and SSDs; the article details its core features, internal components such as MemTable and Bloom filters, and real‑world uses in TiDB and Apache Flink.
