Ein umfassender Vergleich von PostgreSQL und MySQL

Einführung

Werfen wir einen kurzen Blick auf PostgreSQL und MySQL. Bei beiden handelt es sich um wichtige relationale Open-Source-Datenbankverwaltungssysteme, die in verschiedenen Anwendungen weit verbreitet sind.

Technische Architektur und Designphilosophie

Ursprünge und Entwicklung

PostgreSQL entstand 1986 aus dem POSTGRES-Projekt in Berkeley, dessen Ziel es war, Datenbankverwaltungssysteme durch gründliche akademische Forschung und strenge SQL-Standards voranzutreiben. Dieser Hintergrund bietet PostgreSQL eine solide theoretische Grundlage mit Schwerpunkt auf Datenkonsistenz und macht es ideal für komplexe Abfragen und erweiterte Datentypen. Sein Design legt Wert auf langfristige Stabilität, Skalierbarkeit und von der Community vorangetriebene Innovation.

Im Gegensatz dazu wurde MySQL 1995 von Michael Widenius und David Axmark entwickelt, wobei Praktikabilität und Benutzerfreundlichkeit im Vordergrund standen, um den Anforderungen sich schnell entwickelnder Internetanwendungen gerecht zu werden. Es vereinfacht die Datenbankverwaltung und steigert die Leistung und wird während des Internetbooms schnell zur bevorzugten Wahl für Webentwickler. Der Fokus von MySQL lag stets auf Leistung und einfacher Bereitstellung.

Datenbank-Engines

Die bemerkenswerte Funktion von MySQL ist die Unterstützung mehrerer Datenbank-Engines, sodass Benutzer die beste Speichermethode für ihre Anforderungen auswählen können. Seit Version 5.5 ist InnoDB die Standard-Engine und unterstützt Transaktionen und Sperren auf Zeilenebene für hohe Parallelität und Datenkonsistenz. MyISAM bietet zwar eine bessere Leseleistung, verfügt jedoch nicht über Transaktionsunterstützung und ist für leseintensive Szenarien geeignet. MySQL bietet auch Engines wie Speicher und Archiv für bestimmte Anwendungsfälle.

PostgreSQL hingegen verwendet eine einheitliche Kern-Engine, die Konsistenz und Interoperabilität für alle Funktionen gewährleistet. Dieses Design unterstützt komplexe Abfragen, Transaktionsmanagement und erweiterte Datentypen und vereinfacht gleichzeitig die Wartung. Obwohl in einigen Fällen weniger flexibel als MySQL, werden die interne Flexibilität und Skalierbarkeit von PostgreSQL durch Funktionen wie Partitionierung und Abfrageoptimierung verbessert.

Vergleich der SQL-Syntax und -Funktionen

Eine Vergleichsanalyse zeigt Unterschiede und Gemeinsamkeiten in Bereichen wie Array-Typ-Unterstützung, JSON-Verarbeitung, Transaktionsverwaltung, temporäre Tabellen, Fensterfunktionen, rekursive Abfragen, Datentypreichtum, Standardwertbeschränkungen und Groß-/Kleinschreibung:

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 diverse 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.

Nota: Dari masa ke masa, kedua-dua sistem sentiasa dikemas kini dan sokongan serta prestasi ciri tertentu mungkin berubah. Sebaiknya rujuk dokumentasi rasmi terkini atau nota keluaran semasa memilih pangkalan data.

Perbandingan Ciri Lanjutan: Jenis Data dan Pengendalian Transaksi

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.

Jenis Data dan Ciri Fungsian

• Jenis Data Terperinci: PostgreSQL menawarkan pilihan yang lebih kaya seperti tatasusunan, JSONB, hstore, menjadikannya sesuai untuk pengendalian data yang kompleks.
• Fungsi Tetingkap dan Pertanyaan Analitik: PostgreSQL telah menyokong ini lebih awal, manakala MySQL menambahnya dalam keluaran yang lebih baharu.
• Pengendalian Transaksi dan Kawalan Keselarasan: Membandingkan tahap pengasingan mereka, pelaksanaan MVCC dan mekanisme penguncian menunjukkan perbezaan utama.

Perbandingan Prestasi dan Kebolehskalaan

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.

Perbandingan Mendalam Prestasi dan Kebolehskalaan

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. - 内置和第三方连接池管理优化资源使用和响应时间。 - 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.

Prestasi dan Kebolehskalaan

• Penanda Aras dan Beban Kerja: Analisis prestasi kedua-dua sistem di bawah beban kerja yang berbeza, menyebut kelebihan MySQL dalam konteks baca-berat dan kecekapan PostgreSQL dalam pertanyaan yang kompleks.
• Skalabiliti: Bincangkan keupayaan skala mendatar mereka: strategi sharding MySQL berbanding fungsi pengumpulan sambungan, pembahagian dan pertanyaan selari PostgreSQL.

Perbandingan Keselamatan dan Pematuhan

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.

Keselamatan dan Pematuhan

• Pengurusan Kebenaran Pengguna: PostgreSQL cemerlang dengan kawalan terperinci dan keselamatan peringkat baris. MySQL memfokuskan pada penyesuaian keselamatan lapisan aplikasi.
• Ciri Penyulitan: Kedua-duanya menyokong SSL/TLS, tetapi PostgreSQL menyertakan pilihan TDE melalui sambungan dan kawalan lanjutan ke atas penyulitan peringkat medan.
• Persijilan Pematuhan: Kedua-dua pangkalan data mematuhi pelbagai piawaian keselamatan, tetapi PostgreSQL mempunyai rangkaian pensijilan yang diiktiraf yang lebih luas, manakala versi perusahaan MySQL meningkatkan keupayaan pematuhan.

Senario Aplikasi dan Syor Pemilihan

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.

Rangka Kerja Membuat Keputusan

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

Pertimbangan

Apabila memilih pangkalan data, tiada satu saiz yang sesuai untuk semua. Sebaliknya, fokus pada perkara yang paling sesuai untuk keperluan anda. Semasa menimbang faktor ini, pertimbangkan untuk menjalankan Bukti Konsep (POC) berskala kecil untuk menguji prestasi pangkalan data di bawah beban kerja tertentu sebelum membuat keputusan muktamad anda. Selain itu, kedua-dua sistem pangkalan data sentiasa menambah baik dan memperkenalkan ciri baharu, jadi sentiasa dikemas kini dengan perkembangan terkini adalah penting untuk membuat pilihan termaklum.

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