docs(notes): update db2 history en content

Author: lzwjava

notes/2025-03-24-db2-history-en.md

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-title: db2-history
+title: History of IBM Db2
 lang: en
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+---
+
+IBM Db2 has a rich history spanning over four decades, evolving from a mainframe relational database to a multi-model, cloud-native platform. Below is an overview of its history, major releases, key functionality milestones, and strategic shifts.
+
+---
+
+### **History Overview**
+- **Origins (1983)**: Db2 began as **DB2 for MVS/ESA** in 1983, named "Database 2" to distinguish it from IBM’s older hierarchical database (IMS). It was among the first commercial relational databases to use **SQL**, inspired by Edgar F. Codd’s relational model.
+- **Mainframe Dominance**: Initially focused on IBM mainframes, Db2 became a cornerstone for enterprises requiring high-performance, transactional systems.
+- **Expansion (1990s–2000s)**: Db2 expanded to UNIX, Windows, and Linux, competing with Oracle and Microsoft SQL Server.
+- **Rebranding (2017)**: Renamed **IBM Db2** to reflect modernization, with a focus on AI, cloud, and hybrid environments.
+
+---
+
+### **Major Releases & Key Features**
+1. **DB2 for MVS (1983)**:  
+   - First SQL-based relational database for mainframes.  
+   - Introduced ACID compliance and centralized data management.
+
+2. **DB2 Version 2 (1988)**:  
+   - Added **stored procedures**, **triggers**, and **referential integrity**.
+
+3. **DB2 Version 3 (1993)**:  
+   - **Object-relational features**: Support for user-defined types (UDTs) and large objects (BLOBs/CLOBs).  
+   - Distributed database support via **DRDA** protocol.
+
+4. **DB2 Version 4 (1994)**:  
+   - **Data partitioning** for scalability.  
+   - Query parallelism for performance.
+
+5. **DB2 Universal Database (Version 5, 1995)**:  
+   - Became a **multi-platform** database (UNIX, Windows, AS/400).  
+   - Supported text, images, and spatial data (object-relational model).
+
+6. **DB2 Version 6 (1997)**:  
+   - **Java support** (JDBC, stored procedures).  
+   - OLAP extensions for analytics.
+
+7. **DB2 Version 7 (1999)**:  
+   - **Materialized Query Tables (MQTs)** for faster queries.  
+   - Enhanced OLAP and data warehousing.
+
+8. **DB2 Version 8 (2002)**:  
+   - **Autonomic computing** (self-tuning, self-healing).  
+   - **Federation**: Query across heterogeneous databases.
+
+9. **DB2 9.1 (2006)**:  
+   - **pureXML**: Native XML storage and XQuery support.  
+   - **Row/column compression**.
+
+10. **DB2 9.5 (2007)**:  
+    - **Deep Compression** (up to 80% storage reduction).  
+    - Integration with IBM’s InfoSphere for data governance.
+
+11. **DB2 10.1 (2012)**:  
+    - **BLU Acceleration**: In-memory columnar processing for analytics.  
+    - **Time Travel Query** for historical data.
+
+12. **DB2 10.5 (2013)**:  
+    - **NoSQL capabilities** (JSON support).  
+    - **Columnar tables** for hybrid transactional/analytical workloads.
+
+13. **Db2 11.1 (2016)**:  
+    - **Machine Learning** integration.  
+    - **Always-on encryption**.
+
+14. **Db2 11.5 (2019)**:  
+    - **Cloud-native deployment** (Kubernetes, Red Hat OpenShift).  
+    - **AI-powered optimization** (IBM Watson).
+
+15. **Db2 Updates (2020s)**:  
+    - **Db2 on Cloud**: Fully managed SaaS.  
+    - **PostgreSQL compatibility** (2022) to attract open-source users.
+
+---
+
+### **Functionality Evolution**
+1. **From Relational to Multi-Model**:  
+   - Expanded from SQL tables to **XML** (pureXML), **JSON**, graph, and time-series data.
+
+2. **Performance Innovations**:  
+   - **BLU Acceleration** (in-memory columnar processing).  
+   - **Compression** and **parallel query execution**.
+
+3. **Cloud & Hybrid Focus**:  
+   - Shifted from on-prem to hybrid cloud, with offerings like **Db2 Warehouse on Cloud** and serverless options.
+
+4. **AI/ML Integration**:  
+   - Embedded machine learning (e.g., automated tuning, anomaly detection).
+
+5. **Open Source & Compatibility**:  
+   - PostgreSQL compatibility (2022) and Kubernetes support to align with modern ecosystems.
+
+---
+
+### **Strategic Shifts ("Reversals")**
+1. **Cloud Pivot**:  
+   - Transitioned from traditional licensing to **Db2-as-a-Service** (DaaS), competing with AWS Aurora and Azure SQL.
+
+2. **Open-Source Embrace**:  
+   - Added **PostgreSQL compatibility** to attract developers, reversing IBM’s historical proprietary approach.
+
+3. **Multi-Model Expansion**:  
+   - Moved beyond relational models to support JSON, XML, and graph, adapting to polyglot persistence trends.
+
+4. **AI-Driven Automation**:  
+   - Integrated AI/ML for autonomous features (e.g., self-optimizing databases), reducing reliance on manual DBA tasks.
+
+---
+
+### **Legacy & Impact**
+Db2 remains a leader in reliability for mission-critical systems (e.g., banking, healthcare). Its evolution reflects IBM’s adaptability—from mainframes to hybrid cloud, SQL to AI—while maintaining core strengths in security and scalability.