A mysterious issue where some MySQL queries return only one row after executing SET SQL_SELECT_LIMIT=1 is traced to the MySQL driver’s Statement.setMaxRows method, which sets a session variable that can pollute pooled connections, leading to unexpected row limits.
This article explains why traditional database connection pools rely on blocking I/O and connection pooling instead of leveraging IO multiplexing, covering JDBC limitations, protocol constraints, ecosystem factors, and the trade‑offs between performance and code complexity.
To overcome export failures when report data exceeds ten thousand rows, this guide demonstrates how to configure MyBatis for forward-only streaming reads by adjusting JDBC settings, adding ResultHandler callbacks, and modifying mapper XML, enabling efficient memory usage during large result set processing.
The article explains why traditional Java database connection pools rely on blocking I/O instead of IO multiplexing, covering JDBC's design, session management, resource constraints, and the practical challenges of adopting non‑blocking approaches in mainstream backend systems.
This article explains why Java database connection pools typically use blocking I/O and connection pooling instead of IO multiplexing, covering JDBC's design, session management, ecosystem constraints, and the trade‑offs between performance and code complexity.
The article analyzes why HiveServer2 experiences JDBC connection failures and task execution stalls under high concurrency, reproduces the issues using GC monitoring and large join queries, and presents memory‑ and GC‑tuning solutions including server migration and JVM parameter adjustments to improve stability.
This article introduces SPL, an open‑source Java‑embeddable computation library that outperforms traditional embedded databases and DataFrame tools by handling both tabular and nested JSON data, supporting JDBC, SQL‑like queries, multi‑source integration, and persistent .btx files with concise code examples.
This tutorial walks through setting up a Spring Authorization Server in a Spring Boot servlet project, adding required dependencies, configuring filter chains, persisting OAuth2 clients, authorizations, and consents with JDBC, and defining JWK sources and provider settings for a complete OAuth2 authorization server.
This article explains MySQL's character encoding workflow, illustrates why queries containing Chinese characters fail without proper settings, and shows how to configure JDBC URLs, server variables, and Docker‑based MySQL instances to ensure lossless UTF‑8 handling.
This article demonstrates how to combine multiple exception types in a single catch block and how to employ Java's try‑with‑resources construct to automatically close resources, providing complete code examples drawn from Nacos's BaseDatabaseOperate class.
The article presents a senior architect’s detailed comparison of Java persistence solutions—JOOQ, MyBatis, Hibernate, JPA, and JDBC Template—examining SQL encapsulation, DSL support, cross‑database portability, security, and practical trade‑offs, ultimately recommending JDBC Template for the project.
This article provides a comprehensive guide on using ShardingSphere-JDBC for read‑write splitting, configuring MySQL master‑slave replication with Docker, explaining redo log and binlog mechanisms, demonstrating two‑phase commit, and showing how to implement database sharding and distributed primary keys in a Spring Boot application.
The article evaluates major Java persistence solutions—Hibernate, MyBatis, JOOQ, Ebean, Spring Data JPA and JDBC Template—by comparing their SQL encapsulation, DSL support, cross‑database portability, performance, and security, ultimately recommending JDBC Template for the author's project.
This guide introduces DBeaver, a free open‑source database management tool, covering its cross‑platform installation, how to create and configure database connections (including JDBC driver handling), and the steps to generate entity‑relationship diagrams from existing databases.
This article explains how to modify JMeter's source code so that the JDBC Request sampler returns results in a clean JSON format, covering environment setup, code changes, building the custom JAR, integration, and the resulting improvements in readability and automation.
This article introduces ShardingSphere‑Jdbc as a lightweight Java JDBC framework, details step‑by‑step Docker‑based MySQL master‑slave replication configuration, reviews redo log and binlog mechanisms, explains two‑phase commit, and demonstrates read‑write splitting and sharding strategies with Spring Boot examples.
This article explains Java's reflection mechanism, discusses its strengths and weaknesses, and demonstrates common scenarios such as JDBC connection setup and Spring framework bean loading with clear code examples, helping developers decide when to apply reflection in backend development.
This article demystifies MyBatis transaction handling by explaining the true JDBC methods—setAutoCommit, commit, rollback—and clarifying common misconceptions about create, begin, close, and suspend, while exploring MyBatis’s Transaction, TransactionFactory, and practical code examples that illustrate how commits, rollbacks, and connection closing behave in various scenarios.
Java developers often mishandle SQL, leading to performance, correctness, and maintenance issues; this article outlines ten common pitfalls—from misunderstanding NULL and misusing UNION to neglecting MERGE and batch inserts—and provides practical solutions to write efficient, reliable database queries.
The PostgreSQL JDBC Driver (PgJDBC) version 42.2.21 introduces documentation updates for the deprecated DataSource API, ensures primary keys for updatable result sets, adds asynchronous notification handling, rewrites the OSGi bundle activator, and fixes metadata retrieval when search_path is not specified.
The article outlines ten frequent errors that Java programmers encounter when writing SQL—ranging from misunderstanding NULL handling to misusing UNION, pagination, and batch inserts—and provides practical solutions to improve correctness, performance, and maintainability of database interactions.
This article outlines ten frequent errors Java programmers encounter when writing SQL, explains why each mistake occurs, and provides practical solutions to improve correctness, performance, and maintainability of database interactions in Java applications.
An in‑depth comparison of popular Java DAO frameworks—including JDBC, JOOQ, MyBatis, Hibernate, and Spring Data—covers their core concepts, code examples, ideal use cases, and limitations, helping developers choose the most suitable data‑access layer for their projects.
This article walks through three data‑sync strategies for Elasticsearch, then details a complete Logstash JDBC configuration to pull Oracle records into an ES index, including setup, parameter explanations, startup commands, and verification via Kibana.
This article analyzes the root causes of MySQL 'wait_timeout' related exceptions in a backend system using MHA read/write separation, explains how oversized connection pool timeout settings and MySQL wait_timeout lead to idle connections being closed, and provides practical Druid configuration adjustments and alternative solutions to eliminate the errors.
EasyJDBC is a Java library built on Spring's JdbcTemplate that adds JPA‑style annotations, dynamic entity mapping, chainable query APIs, and broad database support, with Maven coordinates for both core and Spring Boot starter packages and a detailed changelog for version 2.1.0.
This article explains how JDBC evolves into MyBatis, detailing the seven-step JDBC process, the motivations for encapsulating JDBC, the design of MyBatis components such as SqlSession, Executor, and StatementHandler, and various optimization strategies including connection pooling, SQL management, dynamic parameters, and caching.
This guide introduces DBeaver, a free open‑source database management tool, explains how to download and install it on various operating systems, shows how to create and test database connections (e.g., PostgreSQL), manage JDBC drivers, and generate ER diagrams from existing schemas.
DeWu chose the open‑source time‑series database TDengine to store billions of daily Sentinel flow‑control metrics, using a super‑table design with per‑resource tables, a three‑node cluster, Druid/MyBatis pooling, and raw‑SQL writes, achieving 10 ms batch write latency, sub‑millisecond queries, and 90 % compression.
The article provides a comprehensive technical guide on Flink's FileSystem, JDBC, and Kafka connectors, detailing their source and sink implementations, core code logic, checkpoint handling, partition commit strategies, and complete SQL usage examples for streaming applications.
This article analyzes the intermittent “Public Key Retrieval is not allowed” error in MySQL 8.0 when using JDBC, C3P0, or Druid connections, explains the authentication plugins involved, and provides step‑by‑step configuration fixes and best‑practice recommendations.
This article explains why Java applications occasionally encounter the "Public Key Retrieval is not allowed" error when connecting to MySQL 8.0, analyzes the role of caching_sha2_password and user authentication cache, and provides practical solutions such as specifying the RSA public key, enabling AllowPublicKeyRetrieval=True, or switching to mysql_native_password.
This article introduces Apache IoTDB, a high‑performance time‑series database for IoT, covering its key features, overall architecture, installation procedures, command‑line operations, and JDBC usage with example code to help newcomers quickly start storing and querying sensor data.
This article introduces DBeaver, a free open‑source, Java‑based universal database client that supports a wide range of databases via JDBC, outlines its rich features, and provides step‑by‑step installation and connection setup instructions for Windows, macOS, and Linux.
This article introduces DBeaver, a free open‑source, cross‑platform database management tool that supports numerous databases via JDBC, outlines its rich features such as data editors, ER diagrams, import/export, and provides step‑by‑step installation instructions for Windows, macOS, and Linux, plus tips for creating connections.
This guide explains how to download, install, and configure DBeaver, connect to various relational and NoSQL databases via JDBC, manage drivers manually when needed, and generate entity‑relationship diagrams directly from existing database schemas.
This article introduces DBeaver, a free open‑source, Java‑based database management and development tool that supports a wide range of databases via JDBC, outlines its rich features, provides installation instructions for Windows, macOS, and Linux, and walks through creating and using a database connection with screenshots.
This article introduces DBeaver, a Java‑based, cross‑platform, open‑source database client that supports a wide range of JDBC and non‑JDBC data sources, outlines its key features, provides installation steps for Windows, macOS, and Linux, and shows how to create and use database connections.
This article introduces DBeaver, a free open‑source, Java‑based universal database management and development tool, outlines its rich features, supported databases, and provides step‑by‑step installation and connection setup instructions for Windows, macOS, and Linux environments.
This article reviews Java persistence technologies, shows how raw string concatenation in JDBC, MyBatis, JPA/Hibernate and native SQL can lead to SQL injection, and provides concrete safe‑coding patterns such as PreparedStatement, #{ } bindings, named parameters, and dynamic‑SQL safeguards.
This tutorial introduces Apache Zeppelin, explains REPL and Jupyter concepts, outlines its core features and project structure, and provides step‑by‑step instructions for installing Zeppelin, creating notebooks, and connecting to databases, Spark, and Flink with practical code examples.
This article introduces Apache ShardingSphere's architecture—including ShardingSphere‑JDBC, ShardingSphere‑Proxy, and the upcoming Sidecar—explains data sharding principles, read/write splitting, and provides a complete Spring Boot example with Maven dependencies, Java source code, and configuration files for horizontal database partitioning.
This article explains the real JDBC transaction methods, clarifies common misconceptions about transaction states in MyBatis, details the MyBatis Transaction and TransactionFactory interfaces, and explores special scenarios such as auto‑commit false, missing commit or close, with concrete code examples.
This article explains how MyBatis loads and categorizes logging implementations, details the role of SLF4J and other frameworks, describes the LogFactory adapter selection process, and shows how JDBC log proxies use dynamic proxies to output SQL execution details.
This article explains the difference between APIs and Java SPI, describes how SPI enables plug‑in development through ServiceLoader, and illustrates its practical use with JDBC driver loading and Flink table factories, providing code snippets and implementation steps for backend developers.
This guide walks you through installing the free, open‑source DBeaver client, configuring JDBC connections for databases such as PostgreSQL, and using its built‑in tools to create ER diagrams, covering essential steps, tips, and common pitfalls.
This guide introduces DBeaver, a free open‑source Java‑based database management tool, covering its features, cross‑platform installation, how to create connections (e.g., PostgreSQL), test drivers, and generate ER diagrams, along with useful resource links.
Learn how to install the open‑source DBeaver tool, configure connections for databases such as PostgreSQL and Oracle via JDBC, manage drivers, and generate entity‑relationship diagrams, with step‑by‑step screenshots and links to official site and GitHub repository.
This article explains the core ideas of Java reflection, demonstrates how to obtain Class objects, create instances, access fields and methods, and discusses common use cases such as Spring IoC, factory patterns, and JDBC driver loading, while also covering its advantages, drawbacks, and best‑practice tips.
This guide walks you through downloading and installing DBeaver, setting up connections to various databases—including PostgreSQL, Oracle, and NoSQL platforms—using JDBC drivers, and creating ER diagrams, providing step‑by‑step instructions and screenshots to help you manage and visualize your data efficiently.
This article introduces DBeaver, a free open‑source Java‑based database management tool, covering its cross‑platform installation, JDBC support for a wide range of relational and NoSQL databases, step‑by‑step connection setup, and how to generate ER diagrams from existing schemas.
This guide introduces DBeaver, a free open‑source Java‑based database management tool, explains how to download and install it on various operating systems, shows how to create connections to many relational and NoSQL databases via JDBC, and demonstrates generating ER diagrams from existing schemas.
This article analyses the root cause of generic "exception" errors during article publishing caused by mismatched MySQL wait_timeout and Druid JDBC pool settings, explains the impact of these parameters, and provides step‑by‑step configuration adjustments and alternative solutions to stabilise the backend database connection pool.
This article explains what MyBatis TypeHandler is, how to configure the environment, create custom handlers, register them via Spring Boot or XML, and details the internal execution flow for converting parameters and results between Java and JDBC types.
This article introduces Apache Phoenix, an open‑source SQL layer for HBase that enables JDBC‑based table creation, data insertion and querying, while supporting secondary indexes, transactions and various optimizations, and outlines a series covering its syntax, tools, best‑practice and real‑world use cases.
The article examines a severe database performance slowdown caused by excessive library cache locks, traces it to improper JDBC ResultSetType settings that introduce unwanted ROWID columns during SQL parsing, and presents systematic experiments across various queries, ResultSetType values, JVM configurations, and database versions to recommend optimal parameter choices.
This article explains Java's reflection mechanism, covering how to obtain Class objects, the java.lang.reflect API, practical code examples, common use cases such as dynamic proxies, JDBC driver loading, Spring bean initialization, and discusses the advantages and performance drawbacks of using reflection.
The article analyzes a MySQL 5.7 upgrade that broke an application due to SSL being enabled by default in version 5.7.28, explains how the JDBC useSSL=true setting triggered handshake errors, and provides several practical solutions such as disabling SSL, adjusting auto‑generation settings, and updating the connection string.
This article provides a comprehensive guide to JDBC, covering its definition, core interfaces (Connection, Statement, ResultSet), the advantages of PreparedStatement, the need for connection pools, pagination techniques for Oracle and MySQL, and practical usage of DBUtils with full code examples.
This article explains the difference between Java's Class.forName and ClassLoader when loading classes, shows how the initialize flag controls static initialization, provides code examples, and discusses practical scenarios such as Spring IoC and JDBC driver registration.
This article explains how to use ShardingSphere‑JDBC to achieve horizontal database sharding and read/write splitting in a Spring Boot application, covering ShardingSphere concepts, configuration, entity and DAO code, custom sharding algorithm, and practical testing with multiple MySQL instances.
This article explains Spring Boot’s @Transactional implementation, covers transaction isolation levels and propagation, walks through the core source code of TransactionInterceptor and PlatformTransactionManager, and guides you step‑by‑step to create a custom annotation that rolls back on specified exceptions using JDBC and AOP.
Learn how to replace verbose JDBC code with Spring’s JdbcTemplate by first understanding JDBC basics, then adding the necessary Maven dependencies, configuring a connection pool, defining entity and repository classes, and writing unit tests, all illustrated with complete Java examples.
This tutorial explains how to integrate JDBC into a Spring Boot project, covering Maven dependencies, MySQL driver setup, application.yml datasource configuration, Spring Boot's auto‑configuration mechanism, JdbcTemplate usage, Swagger documentation, CRUD endpoint implementation, and solutions to typical connection errors.
This guide explains how to integrate JDBC into a Spring Boot project, covering Maven dependencies, datasource configuration, Spring Boot's auto‑configuration mechanism, JdbcTemplate usage, Swagger setup for API testing, CRUD examples on a MySQL department table, and solutions to typical connection errors.
This article explains Java persistence technologies—including JDBC, MyBatis, JPA, and Hibernate—highlights common patterns that cause SQL injection, and provides concrete techniques such as parameterized PreparedStatement, MyBatis #{ } binding, dynamic SQL whitelisting, and proper JPA/Hibernate query parameter usage to securely handle user input.
This guide walks you through adding Alibaba's Druid connection pool to a Spring Boot project, configuring its properties, enabling built‑in monitoring via Actuator, and accessing the Druid dashboard to observe datasource and SQL performance metrics.
This article explains the concept of a DataSource, compares it with core JDBC APIs, and provides a step‑by‑step guide to configuring Spring Boot 2.x’s default HikariCP connection pool, including common properties, their meanings, and links to full example projects.
This article demystifies MyBatis transaction handling by clarifying the true JDBC transaction methods, explaining Spring's propagation concepts, detailing the MyBatis Transaction and TransactionFactory interfaces, showcasing code examples, and exploring special cases such as auto‑commit nuances and connection‑pool interactions.
This article presents a comprehensive multi‑threaded performance and safety evaluation of four popular database connection pools—Druid, JNDI, Tomcat, and Oracle UCP—across Tomcat, WebSphere, and JWS servers, detailing test setup, methodology, results, and best‑practice recommendations for proper pool usage.
This article explains how to overcome Spark SQL's inability to handle certain Oracle data types, such as Timestamp with local timezone and FLOAT(126), by creating and registering a custom JdbcDialect that remaps unsupported types to compatible Spark types.
This article explains JDBC fundamentals, detailing its core interfaces such as Driver, Connection, Statement, PreparedStatement, and CallableStatement, outlines transaction isolation levels, common methods, ResultSet handling, and emphasizes the importance of mastering JDBC for effective use of Java ORM frameworks.
The article explains a 14‑hour discrepancy between MySQL's created_time and recovery_time timestamps, analyzes JVM and driver timezone settings, traces MyBatis and MySQL driver conversions, and provides practical fixes by adjusting MySQL server and JDBC URL timezones.
This guide walks through configuring JMeter to connect to MySQL and Oracle databases via JDBC, covering driver installation, JMeter component setup, request creation, result verification, and troubleshooting common connection errors for performance testing.
This article explains the evolution of Spark SQL from Shark, describes its key features such as SchemaRDD and in‑memory columnar storage, compares row‑based and column‑based storage, and provides practical Scala code examples for creating DataFrames and loading data from various sources.
Apache Phoenix is an open‑source SQL layer for HBase that lets developers use standard JDBC instead of the native HBase client API, offering features such as secondary indexes, transactions, and various SQL‑level optimizations while supporting full table creation, insertion, and querying.
This article examines the enterprise‑level open‑source distributed middleware DBLE (aka MyCat Plus), explains MySQL 5.1 prepared‑statement protocol, details DBLE’s implementation and two reported bugs (#1122 and #1124), analyzes their root causes, and presents the fixes released in version 2.19.03.0.
This guide outlines the four progressive stages of Java database development—basic JDBC usage, framework integration, performance tuning, and high‑availability architecture—providing practical techniques, tools, and best practices for building robust backend data systems.
This article analyzes how MySQL's shared temporary tablespace (ibtmp1) grows when JDBC connections use the useCursorFetch=true parameter, demonstrates the resulting query failures and silent sleeps, compares segment‑fetch and stream‑fetch approaches, and proposes configuration and coding solutions to control temporary space usage and ensure proper error reporting.
This article presents a complete Java Swing‑based student information management system, detailing the MySQL database schema, JDBC CRUD operations, model classes, DAO layer, utility classes, and a Swing UI, providing a practical example for building desktop applications with database integration.
This tutorial walks through creating a Spring Cloud Config Server that stores configuration data in a MySQL database, covering project setup, Maven dependencies, database schema creation with Flyway, Java bootstrap code, application properties configuration, and verification using curl commands to retrieve configuration values.
This article provides a comprehensive technical overview of Sharding-Proxy, covering its transparent MySQL‑protocol design, internal architecture, PreparedStatement optimization, HikariCP tuning, result‑set streaming, memory‑strict and connection‑strict modes, and practical configuration tips for high‑performance database proxying.
This article explains why creating a database connection for each request is inefficient, introduces the concept and configuration of connection pools, provides a custom Java DataSource implementation, and demonstrates the use of popular open‑source pools such as DBCP, C3P0, and Tomcat JNDI with complete code examples.
This article presents a detailed Java learning roadmap that starts with front‑end basics, progresses through core Java SE concepts, object‑oriented programming, databases, web technologies, major frameworks, and advanced topics such as JPA, Lucene, and high‑performance architecture, offering a structured path for aspiring developers.
This article explains the motivations, scenarios, architecture, core components, performance characteristics, and future roadmap of Sharding-JDBC, a lightweight Java framework that enables transparent database sharding and scaling for high‑volume, high‑concurrency applications.
This article explains why MySQL throws "Incorrect string value" when storing emojis, how utf8mb4 solves the problem, and provides step‑by‑step instructions—including table conversion, my.cnf changes, connector upgrades, and runtime workarounds—for reliable emoji storage.
This article examines three real‑world MySQL deadlock incidents—unique‑key null insertion, concurrent duplicate‑key insertion, and a JDBC parameter bug—detailing their detection, analysis, and the concrete fixes applied to prevent recurrence.
This article, the fifth in a static code scanning series, explains six special scenarios—custom close utilities, methods returning resources, streams that need not be closed, nested stream closures, JDBC statement/result set relationships, and socket streams—that complicate determining whether Java resources have been properly closed.
This article explains how to configure client‑side and server‑side Connect Time Load Balancing for Oracle RAC across versions, details the role of SCAN, local_listener and remote_listener settings, describes Runtime Connection Load Balancing with FAN and LBA events, and shows how to tune TCP timeout parameters.
This article explains the principles, architecture, and performance of Sharding-JDBC, covering sharding scenarios, rule configuration, JDBC rewriting, SQL parsing and routing, result merging, and future roadmap, while comparing it with other open‑source sharding solutions.
Phoenix adds a SQL layer to HBase, enabling easy table creation, data import, and complex queries via JDBC, with features like secondary indexes and integration with Spark, Hive, and more, illustrated through step‑by‑step examples and sample code.
MySQL normally loads an entire query result into memory, which can cause out‑of‑memory errors on large tables, but by adding the -q option in the console, enabling useCursorFetch in JDBC URLs, and setting stmt.setFetchSize(Integer.MIN_VALUE), you can switch to a streaming mode that returns rows one at a time.
Sharding-JDBC is a client‑side Java framework that provides transparent horizontal sharding for relational databases, offering flexible sharding strategies, SQL parsing and rewriting, multi‑threaded execution, result merging, and high performance while requiring no additional deployment or proxy layers.
