PostgreSQL和MySQL的全面比较

介绍

让我们快速了解一下 PostgreSQL 和 MySQL。两者都是重要的开源关系数据库管理系统，广泛应用于不同的应用。

技术架构和设计理念 起源与发展

PostgreSQL起源于1986年伯克利的POSTGRES项目，旨在通过严格的学术研究和SQL标准来推广数据库管理系统。背景是 PostgreSQL 它为数据一致性提供了坚实的理论基础，使其成为复杂查询和先进数据类型的理想选择。其设计强调社区驱动的长期稳定性、可扩展性和创新。

相比之下，MySQL 由 Michael Widenius 和 David Axmark 创建于 1995 2000年，优先考虑实用性和易用性，以满足快速发展的互联网应用的需求。它简化了数据库管理，提高了性能，并在互联网繁荣时期迅速成为 Web 开发人员的首选。 MySQL 关键始终是性能和易于部署。

数据库引擎

MySQL 其显著特点是支持各种数据库引擎，允许用户根据自己的需要选择最佳的存储方式。InnnoDB自5.5版本以来一直是默认引擎，支持事务和行级锁定，以实现高并发性和数据一致性。 虽然MyISAM提供了更好的阅读性能，但缺乏事务支持，适合阅读密集型场景。 MySQL 还提供了特定用例 Memory 和 Archive 等引擎。

相比之下，PostgreSQL 使用统一的核心引擎，以确保所有功能的一致性和可操作性。该设计支持复杂的查询、事务管理和先进的数据类型，并简化维护。虽然在某些情况下不如 MySQL 灵活，但 PostgreSQL 通过分区、查询优化等功能，增强了内部灵活性和可扩展性。

比较 SQL 语法和功能

比较分析揭示了数组类型的支持，JSON 处理、事务管理、临时表、窗口函数、递归查询、数据类型丰富、默认值约束和大小写差异及相似之处：

SQL Syntax/Feature PostgreSQL MySQL Description Array Types Supported Not directly supported PostgreSQL allows direct definition of array type fields. MySQL simulates arrays using strings or other indirect methods. JSON Support Powerful More basic PostgreSQL has advanced JSON support with indexing and optimized queries. MySQL’s JSON support has improved in recent versions but remains simpler. Transaction Handling Fully ACID Default auto-commit PostgreSQL pulls off full ACID compliance by default, ideal for high-consistency scenarios. MySQL defaults to auto-commit for each statement but can be configured for transaction handling. Temporary Tables Session/Global Scope Session Only PostgreSQL allows both session-level and global temporary tables, while MySQL supports only session-level ones. Window Functions Supported Supported since later versions PostgreSQL has long supported window functions; MySQL added full support in more recent versions. CTE (Common Table Expressions) Supported Supported Both support CTE, but advanced usages or performance may vary. Recursive Queries Supported Supported since version 8.0 PostgreSQL has supported recursive queries for a while, while MySQL started in version 8.0. Data Types More varied (like ARRAY, HSTORE, GIS types) Basic types are comprehensive PostgreSQL supports more specialized data types, while MySQL has a good set of basic types but not as perse as PostgreSQL. Default Value Constraints Supports any expression Has many limitations PostgreSQL allows defaults to be any expression, whereas MySQL’s defaults are usually constants. Case Sensitivity Configurable Defaults to case-insensitive PostgreSQL can configure case sensitivity at the database or column level, while MySQL defaults to case-insensitive unless using binary collation.

注：随着时间的推移，两个系统将不断更新，特定功能的支持和性能可能会发生变化。最好查阅最新的官方文件或发布说明。

高级功能比较：数据类型和事务处理

Feature/Database PostgreSQL MySQL Advanced Data Types Supports arrays, JSONB, hstore, etc., for complex data structures. Supports JSON (enhanced in newer versions), but doesn't natively support arrays or hstore, needing indirect methods. Window Functions Early support for window functions, suitable for a variety of complex data analytics scenarios. Added window functions in newer versions, progressively improving functionality but might lag in maturity and community resources. Transaction Isolation Levels Supports READ UNCOMMITTED, READ COMMITTED, REPEATABLE READ, SERIALIZABLE, fully compliant with SQL standards. Also supports these four isolation levels, but defaults to REPEATABLE READ and implements them via different storage engines (like InnoDB). MVCC Implementation Strong MVCC mechanism maintains multiple versions for each row, allowing for lock-free reads to enhance concurrency. InnoDB uses MVCC via Undo Logs to maintain transaction views, optimizing read and write concurrency with its own locking strategies. Locking Mechanism Supports row-level locking combined with multi-version concurrency control, reducing lock contention and improving concurrency efficiency. InnoDB supports row-level locking; MyISAM and other engines use table locks. Row-level locking improves concurrency but can be influenced by locking strategies and transaction designs.

数据类型和功能特征

• 高级数据类型：PostgreSQL 提供了更丰富的选项，如数组、JSONB、hstore，使其适用于复杂的数据处理。
• 窗口函数及分析查询：PostgreSQL 这些已经在早期得到了支持， MySQL 添加到更新版本中。
• 事务处理及并发控制：比较其隔离级别MVCC 显示关键差异的实现和锁定机制。

比较性能和可扩展性

Feature/Database PostgreSQL MySQL Benchmarking and Workload - Excels in complex queries and joins, thanks to rich indexing types and an optimizer. - Good balance for write-heavy and mixed workloads. - Performs excellently in read-heavy scenarios, especially simple SELECT queries. - InnoDB engine optimizes read speed and handles concurrency well. Scalability Strategy - Supports partitioning for large tables to optimize query performance. - Parallel querying enhances large data processing capabilities. - Connection pooling management boosts concurrent processing. - Achieves scalability via third-party tools (like PgPool-II, Patroni) for high availability and extensibility. - Sharding is common for horizontally scaling, ideal for large data distribution. - Offers replication (master-slave), group replication for redundancy and separating reads and writes. Horizontal Scalability - Native support is limited but can implement complex distributed deployments with third-party tools. - Citus extension enables real distributed SQL processing. - Has more mature sharding solutions and clustering technologies, making horizontal scalability more flexible, especially for large internet applications.

深入比较性能和可扩展性

Feature/Database PostgreSQL MySQL Benchmarking and Workload - With a powerful query optimizer and various indexing types, excels in complex query handling and analysis.- Balanced reading and writing, suitable for applications needing high-performance writing and complex analysis.- Excels in read-heavy contexts, particularly in simple SELECT queries, suited for web browsing and content distribution scenarios.- Optimizes read performance through read-write separation and caching strategies. - Specializes in read-heavy operations for simple SELECT queries, perfect for content management systems and e-commerce platforms, ensuring optimized reading performance.- MySQL supports InnoDB optimizations for read speed and concurrency handling. Scalability Solutions - Partitions support range, list, hash, and more, boosting large table query efficiency.- Automatically leverages multi-core CPUs for parallel querying, enhancing data retrieval speed. - 优化资源的使用和响应时间，管理内置和第三方连接池。 - Using extensions like Citus for distributed processing.- Sharding, either manual or automated, disperses storage and processes large datasets to improve read and write performance.- Replication mechanisms (master-slave, group) enhance data availability and reading scalability. - InnoDB Cluster provides integrated high availability and scalability solutions that simplify cluster management.

性能和可扩展性

• 基准测试和工作负载：分析两个系统在不同工作负载下的性能 MySQL 在读取密集型环境中的优势 PostgreSQL 复杂查询中的效率。
• 可扩展性：讨论其水平的可扩展性：MySQL 分片策略与 PostgreSQL 连接池、分区及并行查询功能。

比较安全性和合规性

Feature/Database PostgreSQL MySQL User Permission Management - Fine-grained permission control with role and privilege inheritance, making it easier to manage complex permission structures.- Supports row-level security (RLS) for custom access control rules.- Provides a detailed user and permissions management system, with controls down to the database and table level. - Doesn't natively support row-level security but can implement it through application logic. Encryption Features - Supports SSL/TLS encrypted connections to secure data transmission.- Has field-level encryption plugins to enhance security when data is at rest.- Transparent Data Encryption (TDE) options can be implemented through third-party extensions. - Built-in SSL/TLS support protects network communications.- InnoDB storage engine supports table space encryption to secure data files.- MySQL Enterprise Edition offers more advanced encryption options. Compliance Certification - Complies with multiple security standards, including FIPS 140-2 and Common Criteria.- Supports data protection regulations like GDPR, but specific compliance measures need to be tailored to the environment. - Holds several international security certifications like PCI DSS and ISO 27001.- Supports SSL/TLS and TDE, aiding in compliance with regulations like HIPAA and GDPR.- MySQL Enterprise Edition provides enhanced auditing and security functions to strengthen compliance.

安全与合规

• 用户权限管理：PostgreSQL 擅长细粒度控制和行级安全。 MySQL专注于应用层的安全适应。
• 两者都支持加密功能：两者都支持 SSL/TLS，但 PostgreSQL 通过扩展和对字段级加密的高级控制来包含 TDE 选项。
• 合规认证:两个数据库都遵守各种安全标准，但PostgreSQL认证更广泛，而MySQL的企业版则增强了合规性。

应用场景及选型建议

Database Suitable Scenarios PostgreSQL - Data analytics and business intelligence: Strong capabilities for complex queries, window functions, and geospatial data processing.- High compliance industries like finance and healthcare: Robust security and compliance features.- Complex application development: Supports advanced data types and multi-version concurrency, ideal for transaction-heavy applications. MySQL - Web applications and startups: Lightweight, easy to deploy, rich community resources, quick development cycles.- Read-heavy services: Such as content management systems and e-commerce platforms with optimized read performance.- Cloud-native environments: Deep integration with various cloud providers, suited for quickly scalable internet services.

决策框架

Decision Factor Considerations PostgreSQL Tendency MySQL Tendency Data Scale and Complexity Volume of data, query complexity Large datasets, complex queries, multi-dimensional analysis Small to medium datasets, simple queries Transaction Processing Needs Complexity and consistency of transactions High-concurrency transactions, strict ACID requirements Simple transaction handling, read/write separation scenarios Budget and Costs Software licensing, operational costs Open-source and free, but may require more professional support Open-source and low cloud service costs Team Familiarity and Skills Technical stack match, learning curve Requires strong SQL skills, suited for experienced teams Friendlier for beginners, lower learning curve

注意事项

在选择数据库时，没有一刀切的选择。相反，专注于最适合您需求的内容。在权衡这些因素时，请考虑运行小规模概念验证 (POC)，测试数据库在特定工作负载下的性能，然后做出最终决定。此外，这两个数据库系统都在不断改进和引入新的功能，因此了解最新的发展对做出明智的选择至关重要。

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