This article explains the WebMan HTTP service framework built on Workerman, describes its single‑process, multi‑thread/coroutine, IO‑multiplexing and EventLoop modes, clarifies why it lacks a database connection pool, and presents detailed performance test results under various concurrency levels.
This article explains what MySQL deadlocks are, outlines the four necessary conditions that cause them, provides a concrete example with SQL code, and offers practical strategies such as lock ordering, timeout settings, and MySQL’s built‑in detection to prevent and resolve deadlocks.
This article explains how to implement pagination, multi‑condition fuzzy search, and their combination using Redis Sorted Sets and Hashes, discusses performance optimizations and expiration strategies, and also contains promotional material for ChatGPT services and a community offering.
The 2024 Inclusion·Bund conference brought together academia and industry leaders to discuss how data technologies are evolving and aligning with AI, covering trends in large‑model storage, synthetic data generation, AI‑enhanced databases, and Ant Group's emerging AI‑centric data ecosystem.
This article introduces MyBatis‑Mate, an enterprise‑grade MyBatis extension that provides sharding, data auditing, sensitive‑word filtering, field encryption, dictionary binding, dynamic DDL maintenance, data‑scope permissions and performance monitoring, complete with practical code examples and configuration guidance.
This article explains Redis master‑slave replication, synchronization steps, handling of network partitions, and how Sentinel provides automatic failover through monitoring, leader election, and notification, offering strategies to reduce master load and ensure high availability.
This guide walks through ten essential advanced SQL techniques—including CTEs, recursive CTEs, temporary functions, CASE‑WHEN pivots, EXCEPT vs NOT IN, self‑joins, ranking functions, delta calculations with LAG/LEAD, cumulative sums, and date‑time manipulation—to help data professionals ace interview challenges and write cleaner, more powerful queries.
This article explains the design and implementation of MySQL's SQL flow‑control feature, covering its purpose, architecture, external commands, rule management, matching logic, data‑access layer, performance considerations, usage guidelines, and known limitations.
This article explains how to troubleshoot a slow OceanBase stored procedure by locating its trace_id, analyzing audit logs to identify non‑cached UPDATE statements, revealing that preceding TRUNCATE operations invalidate the plan cache, and finally recommending replacing TRUNCATE with DELETE to restore performance.
This article explains why a LEFT JOIN always returns all rows from the left table, clarifies the difference between ON and WHERE clauses, demonstrates the behavior with multiple SQL examples and code snippets, and highlights the special handling of LEFT/RIGHT/FULL joins versus inner joins.
Gotu’s Redis management platform now runs an unattended 5 AM scheduler that automatically selects and migrates nodes based on priority rules, verifies master‑slave synchronization, and rebalances host memory to stay below safe thresholds, improving utilization, reducing DBA effort, and supporting future auto‑deployment and recovery.
The article traces MariaDB’s evolution from its MySQL roots and community‑driven development, through its NYSE listing, financial performance, restructuring, and the recent K1 Investment Management acquisition, while highlighting key figures, product features, and industry reactions.
This article reviews the SQL enhancements added to SQLite between versions 3.22.0 and 3.26.0, covering boolean literals, window functions, the FILTER clause, INSERT … ON CONFLICT (upsert), column renaming, and related API updates.
This article explains the most common reasons why Spring @Transactional annotations may become ineffective or fail to roll back, covering access‑modifier issues, final methods, internal calls, self‑injection, multithreading, unsupported table engines, mis‑configured propagation, exception handling, nested transactions, large‑transaction problems, and the advantages of programmatic transaction management.
This article explains how to connect to a MySQL database with mysqli_connect, execute queries using mysqli_query, and fetch each row as an associative array with mysqli_fetch_assoc, providing a complete PHP code example and best‑practice tips.
The article explains how Apache Doris 2.0 improves data import performance by redesigning MemTable handling, introducing write‑path optimizations, parallel segment flushing, and a single‑replica load mode that reduces resource consumption and boosts throughput for both single‑ and multi‑concurrent workloads.
This article explains MySQL index classifications, the inner workings of B+‑tree and hash indexes, the differences between clustered and secondary indexes, and advanced concepts such as covering indexes, index push‑down, index merge, cost‑based index selection, and common pitfalls that cause index inefficiency.
This guide provides a comprehensive collection of MySQL command‑line scripts covering database and table export/import, creation, deletion, schema inspection, data manipulation, user privilege management, and common DDL operations, all with practical examples.
This article provides a comprehensive overview of MySQL indexing, covering index classifications, B+Tree and Hash structures, primary and secondary (clustered and non‑clustered) indexes, covering index push‑down, index merge, covering indexes, cost‑based index selection, and common pitfalls that cause index inefficiency.
This article provides a comprehensive guide to MySQL indexing, covering index types, data structures, clustering and non‑clustering indexes, hash indexes, B+Tree mechanics, index lookup, covering indexes, index push‑down, index merge, cost‑based index selection, common pitfalls, and best practices for designing effective indexes.
This article explains why Spring transactions can become ineffective or fail to roll back, covering issues such as wrong method visibility, final methods, internal calls, missing Spring bean registration, multithreading, unsupported table engines, misconfigured propagation, exception handling, and offers practical solutions for each case.
The latest ThinkORM release, now independent from ThinkPHP and requiring PHP 8.0+, introduces extensive JSON handling improvements, new query methods, mutator enhancements, and numerous bug fixes that boost performance and developer experience for PHP database applications.
This article walks you through designing a lightweight, high‑performance MySQL helper class in Python, covering singleton connection management, robust exception handling, logging, context‑managed connections, and practical query/execute methods with example code and usage scenarios.
This article walks through a production‑level OceanBase connection‑timeout incident, detailing how to examine OBProxy logs, capture and analyze network packets with tcpdump and Wireshark, identify a blocked random port, and apply kernel‑parameter fixes to prevent the issue.
This article explains the mechanisms behind MySQL auto‑increment primary keys, why gaps appear after failed inserts, unique‑index violations, transaction rollbacks, and batch operations, and how storage engines and innodb_autoinc_lock_mode settings influence the continuity of generated IDs.
This article explains why MySQL auto‑increment primary keys can become non‑continuous, covering storage mechanisms, unique‑index violations, transaction rollbacks, batch inserts, and step‑size settings, and provides practical examples and diagrams to help developers diagnose and avoid ID gaps.
The article introduces X‑Stor, a cloud‑native NoSQL database service that supports multiple data models and process‑level multi‑tenant isolation, describes its plugin‑based architecture and Request Unit metric, and presents experimental results showing superior performance, effective tenant isolation, and load‑balancing benefits compared with traditional single‑model NoSQL systems.
This article explains how MySQL uses B‑tree‑based indexes, covering balanced binary trees, B‑trees, B+‑trees, various index types, data‑type effects, and best practices for creating and using composite indexes to optimize query performance.
The article reviews MySQL's 29‑year evolution, detailing the 8.0 release’s extensive contributions, new features, bug‑fix statistics, and the vital role of the global community and Oracle’s ongoing investment in both the open‑source edition and the HeatWave cloud service.
StarRocks 3.3.1 introduces a cloud‑native persistent index that moves index files to object storage, eliminates local‑disk constraints, and supports elastic scaling, delivering up to ten‑fold latency improvement over local‑disk indexes in elastic scheduling while matching performance in batch and real‑time imports.
This article explains why Java ORM frameworks are essential for simplifying database access, outlines the critical criteria for selecting the right ORM, compares popular choices such as Hibernate, JPA, EclipseLink, and DataNucleus, and provides a step‑by‑step guide for successful implementation.
The article details how the vivo Game Center’s appointment service migrated billions of rows to a dedicated MySQL database with zero‑downtime by implementing a double‑write strategy via a custom MyBatis interceptor that mirrors updates and queries to the new database, handling full and incremental sync, primary‑key consistency, transaction limits, and final cut‑over steps.
The article shares a graduate's interview experience and provides a comprehensive technical guide covering HTTP/1.x vs HTTP/2 differences, Java socket and HTTP server code, OS I/O buffering vs direct I/O, database concurrency control, Bloom filter principles, Java reflection, annotation usage, and synchronized locking semantics.
This article presents a detailed walkthrough of a MySQL InnoDB deadlock case, covering background, log inspection, data preparation, reproduction steps, lock analysis, root‑cause explanation, and practical solutions to prevent and resolve similar deadlock issues.
This article explains how MySQL InnoDB implements full‑text search using inverted indexes, shows how to create and drop full‑text indexes, and demonstrates the three query modes—Natural Language, Boolean, and Query Expansion—along with their syntax, operators, relevance calculation, and practical examples.
This article explains why the OBOracle "set transaction read only" command provides repeatable‑read semantics, evaluates the behavior of the JDBC conn.setReadOnly(true) setting, and shows how to achieve true repeatable‑read isolation by enabling the oracleChangeReadOnlyToRepeatableRead option in the OceanBase client.
This article introduces ReadySet, an open‑source SQL caching layer for MySQL and PostgreSQL, explains its architecture and advantages, and provides step‑by‑step instructions for installing the Docker image, configuring connections, creating caches, and testing query performance to achieve millisecond‑level response times.
This guide walks through checking the OS architecture, preparing the environment, downloading the appropriate MySQL 5.7 packages for ARM, installing and configuring MySQL, setting up automatic startup and environment variables, initializing the server, securing the root account, and finally configuring master‑slave replication between two servers.
This article recounts L's attempt to change a train ticket, analyzes seat availability across four segments, and presents a minimal SQL model with table creation, data insertion, and a query that determines feasible seat combinations, demonstrating how segment‑wise seat allocation can enable complete journey booking.
This article explains how to achieve idempotent order creation and update by using unique order IDs, database primary‑key constraints, Redis flags, and a version‑column mechanism to detect and prevent duplicate submissions and ABA anomalies in distributed systems.
This guide walks you through why Java remains vital, explains what Spring Boot is, outlines its core features, and provides a detailed learning roadmap covering Java fundamentals, Spring core concepts, web development, AOP, microservices, databases, security, DevOps tools, and deployment strategies for building robust enterprise applications.
This article provides a comprehensive guide to using MyBatis dynamic SQL tags—including foreach, if, choose, trim, selectKey, and sql fragments—explaining their attributes, usage scenarios, and offering detailed Java and XML code examples to improve query flexibility and reduce errors.
This tutorial demonstrates how to perform fundamental Redis operations—including setting, retrieving, and deleting keys, working with hashes, lists, and sorted sets—using Python's redis client and includes complete test code for each scenario.
The article details a zero‑downtime migration of a high‑traffic reservation service from a shared MySQL instance to an isolated database by employing a double‑write strategy implemented through a custom MyBatis plugin, covering full and incremental sync, consistency verification, traffic shifting, and key lessons on primary‑key handling and asynchronous write side‑effects.
This article provides a step‑by‑step analysis of MySQL 8.0.32 InnoDB deadlock logs, covering preparation, log extraction, auxiliary information, transaction details, row‑lock structures, and the final summary, with full SQL examples and code snippets for deep understanding.
This guide walks you through preparing multiple virtual machines, configuring MySQL 8.0 server IDs, setting up both classic and GTID‑based master‑slave replication, and managing replication commands, providing clear code snippets and commands for a reliable MySQL clustering environment.
On August 14, 2024, GitHub experienced a massive site-wide outage caused by a database infrastructure configuration change that disrupted traffic routing, leading to loss of database connections and affecting core services such as Pull Requests, Pages, Copilot, and the API, with full restoration confirmed later that evening.
This guide walks through ten common Redis tasks—setting and getting keys, deleting keys, listing keys, hash, list, set, sorted‑set operations, publish/subscribe, pipeline, and transactions—each illustrated with clear Python redis‑py code examples.
This article explains the concept of database connection pools, why they are needed, their core principles and runtime mechanisms, compares traditional direct connections with pooled connections, and reviews major Java pool implementations such as DBCP, C3P0, Druid and HikariCP along with configuration tips and best‑practice considerations.
This article explains the various moments when InnoDB table and row locks are released during a transaction's lifecycle, covering mismatched WHERE conditions, the two‑phase commit prepare stage, AUTO‑INC locks, and differences across isolation levels in MySQL 8.0.32.
MySQL’s pluggable storage‑engine architecture lets each table use a specific engine, with InnoDB (the default in MySQL 8.x) offering row‑level locking, ACID transactions, foreign‑key support, crash recovery, MVCC and a buffer pool, while MyISAM provides only table‑level locking, no transactions, and is suited mainly for read‑intensive workloads lacking recovery requirements.
This article examines the challenges of fuzzy searching encrypted data and compares three implementation approaches—naïve, conventional, and advanced—detailing their principles, performance implications, storage costs, and security trade‑offs, ultimately recommending the conventional token‑based method for most practical applications.
This article describes a business approval scenario where a company name entered by a business user must be checked for duplicates, and explains how to implement fuzzy matching using MySQL RegExp, tokenization with IKAnalyzer, and Java service code to extract, preprocess, match, and rank results by relevance.
This article introduces a Spring‑based asynchronous processing SDK that leverages annotations, transaction event listeners, Kafka, XXL‑Job, and a dedicated database to achieve non‑blocking execution, fault tolerance, and eventual consistency while preserving transaction integrity and providing a clear configuration and usage guide.
This article examines whether a MySQL replica can safely omit setting sync_binlog=1, explains the underlying InnoDB and GTID mechanisms, presents an experiment reproducing power‑loss scenarios, and analyzes how different master_auto_position settings affect data consistency and GTID continuity during recovery.
This article explores the subtle timing of Spring transaction start and commit relative to lock/unlock, demonstrates how improper ordering can cause over‑selling in high‑concurrency scenarios, and provides debugging techniques and practical solutions to ensure atomicity and correct rollback behavior.
This article introduces Easy‑Query, a Java ORM that provides a strongly‑typed, chainable query syntax covering basic CRUD, pagination, joins, sub‑queries, native SQL fragments, group‑by, custom VO mapping and high‑performance encryption, illustrated with extensive code examples and usage notes.
This article provides a comprehensive guide to MySQL's DQL, DML, and DDL sections, explaining execution order, core clauses, and practical code examples for creating, altering, and managing databases and tables.
This article highlights seven world‑class software projects originated by Russian developers—including 7‑Zip, Telegram, Nginx, Kaspersky, JetBrains IDE suite, ClickHouse, and the classic Tetris game—explaining their history, key technologies, and impact on everyday computing.
This article explains what constitutes a slow SQL query, how to detect and analyze it using MySQL tools, and provides practical optimization steps—including indexing, business logic review, caching, scheduling, and partitioning—to dramatically reduce execution time.
This article examines why a scalar subquery in an OceanBase 3.2.3.3 SQL statement takes over 1000 seconds, breaks down the execution plan, identifies the costly nested-loop behavior, and presents a rewrite using WITH and LEFT JOIN that reduces the cost from 788 million to 3.6 million and cuts runtime to about 10 seconds.
MySQL’s TINYINT(1) stores a full byte integer allowing any value from 0‑255 (or –128‑127 signed) and works with arithmetic, offering broad compatibility, while BIT(1) stores a single bit limited to 0 or 1, is MySQL‑specific, and is best used only when true/false storage and minimal space are essential, making TINYINT(1) the generally preferred choice unless strict boolean constraints apply.
This article examines why MySQL pagination using large LIMIT OFFSET values becomes increasingly slow, explains the underlying scanning behavior, and presents six practical optimization techniques—including indexed subqueries, cursor‑based pagination, column selection, partitioning, caching, and hardware considerations—to dramatically improve query performance on massive tables.
This article examines three categories of techniques—naïve, conventional, and advanced—for enabling fuzzy queries on encrypted data, comparing their implementation steps, performance impact, storage overhead, and security trade‑offs, and provides practical examples and reference links for further study.
This article analyzes the problems of scattered property configuration in SpringBoot projects, designs a database table to store configuration items, implements a configuration loader that injects database values into the Spring environment, and demonstrates testing and best‑practice considerations for a robust backend configuration solution.
This article explains how to use PHP's mysqli_query function to perform MySQL operations such as SELECT, INSERT, UPDATE, and DELETE, including a full example that creates a connection, runs a query, processes results, and closes the connection.
StarRocks combines vectorized execution, a new cost‑based optimizer, materialized views, a real‑time storage engine, pipeline execution, and distributed joins to deliver a unified, high‑performance OLAP solution that supports both traditional and lakehouse analytics while reducing operational complexity.
To avoid common MySQL pitfalls, the article compiles practical SQL writing guidelines—selecting specific columns instead of *, using LIMIT 1, avoiding OR in WHERE, optimizing pagination, handling LIKE patterns, minimizing redundant indexes, preferring INNER JOIN, and leveraging covering indexes and EXPLAIN for efficient query execution.
The article details a real‑world backend engineering project where a loan repayment service is refactored to use table sharding with ShardingSphere, covering design decisions, table naming, sharding algorithms, historical data migration, dynamic switches, transaction management, code examples, and practical pitfalls.
This article explains how to speed up SQL queries while keeping statements concise, covering the query processing workflow, optimization goals, and practical tips such as selecting specific columns, avoiding DISTINCT, using proper indexes, preferring EXISTS over COUNT, limiting result sets, favoring WHERE over HAVING, and replacing correlated subqueries with joins.
This guide explains how to set up JDBC drivers, construct connection URLs, use PreparedStatement instead of Statement, iterate ResultSet safely, manage resources with try‑with‑resources, handle transactions, employ connection pools, and properly process SQLExceptions for robust Java database applications.
This article analyzes why two identical DELETE statements on a MySQL table with a unique index can deadlock, explains InnoDB lock types, walks through the execution flow, reproduces the issue with SQL and Java code, and discusses mitigation strategies.
MySQL 9.0, released July 2 2024, introduces EXPLAIN JSON output stored in variables, native EVENT DDL statements, and two new performance‑schema tables for variable metadata, while deprecating the old variables_info columns and removing the mysql_native_password plugin in favor of caching_sha2_password, enhancing observability and security.
This article explains how to obtain the SQL ID, create an outline bound to that ID, and correctly verify its effect in OceanBase, highlighting common pitfalls such as using the wrong schema or relying on EXPLAIN, and provides practical code examples for each step.
LibraDB, the column‑store replica of TDSQL MySQL, has evolved its execution engine from a simple scatter‑gather model to a vectorized SMP pipeline that integrates MPP parallelism, asynchronous I/O, SIMD‑accelerated aggregation and join operators, work‑stealing, and runtime filters, thereby fully exploiting CPU, memory, network and disk resources for both OLTP and analytical queries.
This guide walks through installing pypika and demonstrates how to construct SELECT, WHERE, GROUP BY, JOIN, subqueries, set operations, INSERT, UPDATE, and database‑specific adaptations using Python code, showcasing concrete examples and the full query‑building workflow.
This article explains the motivation behind creating the Easy-Query ORM for Java, demonstrates its fluent query capabilities—including single‑record, list, pagination, joins, sub‑queries, group‑by, native SQL and dynamic condition features—provides extensive code examples, and shares repository links for further exploration.
This tutorial demonstrates how to set up a simple MySQL database, create a Spring Boot project, add Mybatis-Plus dependencies, install the MybatisX plugin, configure the connection, generate entity, mapper, service, and controller code, and verify the integration with a sample REST endpoint.
This guide presents a thorough MySQL performance checklist, covering efficient SQL writing, data‑type choices, selective column retrieval, smart joins, batch inserts, and query‑cache settings; it details key InnoDB and server variable tuning, proper index creation and usage, common pitfalls, and how to analyze and improve queries with EXPLAIN.
This article provides a comprehensive, hands‑on tutorial for planning, installing, configuring, and verifying a PostgreSQL master‑slave (streaming replication) setup on two Linux nodes, including user creation, remote connection settings, data export/import, and troubleshooting tips.
This article explains how two identical DELETE statements on a table with a unique index can cause a deadlock in MySQL 5.7, reviews InnoDB lock types, reproduces the issue with SQL and Java code, and discusses mitigation strategies and behavior changes in MySQL 8.
This article examines why identical DELETE statements on a MySQL table with a unique index can cause deadlocks, reviews InnoDB lock types, reproduces the issue with SQL and Java code, and discusses mitigation strategies such as version upgrades, isolation level changes, and distributed locks.
This article presents 17 versatile Python scripts that automate common tasks such as file management, web scraping, email handling, Excel processing, database interaction, system administration, and more, offering code examples and explanations to help developers and analysts improve productivity.
This guide explains how to set up automated MySQL database backups using a shell script that runs mysqldump (optionally compressed), stores the files on a local disk, makes the script executable, and schedules it with a cron job after verifying disk space and cron availability.
MySQL 9.0 Innovation Edition, released on July 1, 2024, introduces major changes such as the removal of the mysql_native_password plugin, new PREPARE support for event statements, expanded Performance Schema tables, JSON‑formatted EXPLAIN ANALYZE output, Windows installer fixes, and several MySQL Shell enhancements.
This article explains how Redis operates primarily with a single‑threaded model for memory and network operations, why this design is efficient, and how recent versions introduce multi‑threaded components for network I/O, persistence, and asynchronous deletion while preserving thread safety.
Learn how to efficiently import large Excel files into a database using POI, JDBC, MyBatis, and Spring Boot, with step-by-step code examples, performance bottlenecks, and optimization techniques such as caching, asynchronous processing, multi-threaded batch inserts, and thread‑pool configuration for maximum throughput.
This article investigates whether MySQL re‑executes an UPDATE statement that sets a column to its current value, comparing behavior under binlog_format=ROW and binlog_format=STATEMENT with binlog_row_image=FULL, and presents test steps, results, and conclusions.
This article explains why organizations may replace traditional relational databases with Apache Kafka as a system of record, highlighting Kafka's economic, scalable, immutable log capabilities, event replay, flexibility for diverse use cases, and its suitability for highly regulated, data‑intensive environments.
This article explains how to design the database, modify product detail, cart, and order pages, and use Ajax in PHP to enforce purchase quantity limits based on stock levels, ensuring accurate inventory management and improved user experience in online stores.
This article analyzes why distributed transactions are difficult in large‑scale microservice architectures, explains the importance of unique transaction IDs, idempotency, and timeout handling, and presents pragmatic approaches such as local logging, undo‑log tables, NoSQL ID arrays, and selective locking to achieve reliable consistency.
This article explains why upgrading MySQL from 5.7 to 8.0 can cause an "Illegal mix of collations" error in FIND_IN_SET queries, analyzes the root cause, and presents three practical solutions—adjusting server parameters, altering table collations, or rewriting the SQL—to restore correct operation.
This article explains the common slow approach of reading Excel files with POI and inserting rows via JDBC, then presents three practical optimizations—caching data, using asynchronous multithreaded reads, and per‑file async processing—along with thread‑pool configuration tips and EasyExcel examples to dramatically reduce import time from minutes to seconds.
This article walks through MyBatis dynamic SQL tags—foreach, concat, choose, selectKey, if, where, trim, set, and sql fragments—explaining their attributes, usage patterns, and common pitfalls, and provides complete XML and Java code examples for each technique.
While MySQL INT and BIGINT auto‑increment columns usually suffice, this article explains their numeric limits, calculates how many records each can store over time (e.g., at 100 inserts per second), and provides practical steps to switch from INT to BIGINT safely.
This tutorial explains how to connect to a MySQL database using PHP's mysqli extension, execute queries with mysqli_query, and retrieve each row with mysqli_fetch_assoc, providing complete code examples and a full script for efficient database handling.
This article explains why replacing MyBatis with MyBatis‑Plus caused a LocalDateTime conversion exception, identifies the root cause as an outdated mysql‑connector‑java version, and shows how upgrading the connector (to 5.1.37 or later) resolves the issue while providing code examples and debugging steps.
The article examines Peter Zaitsev’s critique of Oracle’s stewardship of MySQL, debunks long‑standing myths, evaluates recent MySQL Heatwave features and performance gaps, and compares MySQL’s trajectory with PostgreSQL and other open‑source databases.
This article explains InnoDB lock concepts, differentiates read and write locks, discusses table‑level versus row‑level locking, and examines how MySQL 5.6 and 8.0 handle adding columns without fully locking tables, highlighting online DDL, atomic DDL, and performance considerations.
MySQL offers a comprehensive set of string functions—including lower, upper, concat, substring/substr, length, char_length, instr, lpad, rpad, trim (with leading, trailing, both options), replace, repeat, reverse, and format—that enable case conversion, concatenation, extraction, padding, trimming, substitution, repetition, reversal, and numeric formatting of textual data.
