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 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.
This article explains Elasticsearch index mapping fundamentals, covering field types such as text, keyword, numeric and date, key index options like analyzer, doc_values, null_value, and multi‑field strategies, and provides concrete code examples and optimization tips for efficient search and storage.
This article compiles 40 core MySQL interview questions covering ACID properties, lock types, views, stored procedures, JOINs, storage engines, query optimization, buffer pools, write buffers, transaction mechanisms, MVCC, isolation levels, gap locks, metadata locks, thread model, row formats, and more, providing concise answers for each.
The article explains Elasticsearch's thread‑pool architecture, detailing the Search, Write, Generic, and other specialized pools, their purposes, fixed or cached configurations, optimization guidelines, and how to monitor and adjust them via REST APIs and built‑in tools.
The article explains Elasticsearch's on‑heap and off‑heap memory design, details each memory pool and its management via LRU, describes Lucene's role in off‑heap storage, and provides practical tips for configuring JVM heap size, cache strategies, and monitoring to achieve stable, high‑performance search.
The article outlines a comprehensive approach to third‑party API design, covering core principles such as security, reliability, usability and extensibility, detailed key‑management and authentication mechanisms, RESTful API specifications, implementation steps with code samples, and best‑practice recommendations for robust and maintainable integrations.
This article explains the concepts, key features, internal implementation, and practical usage of Java's ReentrantReadWriteLock, illustrating how read and write locks interact, how fairness and lock downgrading work, and provides a complete code example with multithreaded readers and writers.
This article explains MySQL's optimizer_switch system variable, how it consists of on/off flags that fine‑tune the query optimizer, shows how to view and modify the flag set, and details the most important flags such as index_merge, ICP, materialization, and others.
