NoSQL
在几年内,NoSQL数据库一直以性能、可扩展性、灵活的模式和分析能力聚焦着人们的注意力。尽管关系型数据库对于某些用例来说仍是一个不错的选择,就像结构数据和要求ACID事务的应用,但是NoSQL在以下用例中将更具优势:
- 存储的数据实质上是半结构化或者松散的。
- 要求一定的等级的性能和扩展性。
- 存取该数据的应用与最终的一致性相吻合。
非关系型数据库典型支持以下功能:
- 灵活的模式
- 无共享架构
- 分片作为数据存储模型的一部分
- 异步复制
- 使用BASE替代ACID事务
InfoQ英文网对当下经常使用的NoSQL数据库进行了盘点:
文档数据库
- MongoDB:开源、面向文档,也是当下最人气的NoSQL数据库。
- CounchDB:Apache CounchDB是一个使用JSON的文档数据库,使用Javascript做MapReduce查询,以及一个使用HTTP的API。
- Couchbase:NoSQL文档数据库基于JSON模型。
- RavenDB:RavenDB是一个基于.net语言的面向文档数据库。
-
MarkLogic:MarkLogic NoSQL数据库用来存储基于XML和以文档为中心的信息,支持灵活的模式。
图数据库
- Neo4j: Neo4j是一个图数据库;支持ACID事务(原子性、独立性、持久性和一致性)
- InfiniteGraph:一个图数据库用来维持和遍历对象间的关系,支持分布式数据存储。
- AllegroGraph:AllegroGraph是结合使用了内存和磁盘,提供了高可扩展性,支持SPARQ、RDFS++和Prolog推理。
-
其他图数据库。
键值数据存储
- Riak:Riak是一个开源,分布式键值数据库,支持数据复制和容错。
- Redis:Redis是一个开源的键值存储。支持主从式复制、事务,Pub/Sub、Lua脚本,还支持给Key添加时限。
- Dynamo:Dynamo是一个键值分布式数据存储。它直接由亚马逊Dynamo数据库实现;在亚马逊S3产品中使用。
- Oracle NoSQL Database:来自Oracle的键值NoSQL数据库。它支持事务ACID(原子性、一致性、持久性和独立性)和JSON。
- Oracle NoSQL Database:具备数据备份和分布式键值存储系统。
- Voldemort:具备数据备份和分布式键值存储系统。
- Aerospike:Aerospike数据库是一个键值存储,支持混合内存架构,通过强一致性和可调一致性保证数据的完整性。
列存储数据库
- Cassandra:Cassandra是列存储数据库,支持跨数据中心的数据复制。它的数据模型提供列索引,log-structured修改,支持反规范化,实体化视图和嵌入超高速缓存。
- HBase:Apache Hbase源于Google的Bigtable,是一个开源、分布式、面向列存储的模型。在Hadoop和HDFS之上提供了像Bigtable一样的功能。
- Amazon SimpleDB:Amazon SimpleDB是一个非关系型数据存储,它卸下数据库管理的工作。开发者使用Web服务请求存储和查询数据项。
- Apache Accumulo:Apache Accumulo的有序的、分布式键值数据存储,基于Google的BigTable设计,建立在Apache Hadoop、Zookeeper和Thrift技术之上。
- Hypertable:Hypertable是一个开源、可扩展的数据库,模仿Bigtable,支持分片。
- Azure Tables:Windows Azure Table Storage Service为要求大量非结构化数据存储的应用提供NoSQL性能。表能够自动扩展到TB级别,能通过REST和Managed API访问。
- 其它列存储数据库。
内存数据网格
- Hazelcast:Hazelcast CE是一个开源数据分布平台,它允许开发者在数据库集群之上共享和分割数据。
- Oracle Coherence:Oracle的内存数据网格解决方案提供了常用数据的快速访问能力,一致性支持事务处理能力和数据的动态划分。
- Terracotta BigMemory:来自Terracotta的分布式内存管理解决方案。这项产品包括一个Ehcache界面、Terracotta管理控制台和BigMemory-Hadoop连接器。
- GemFire:Vmware vFabric GemFire是一个分布式数据管理平台,也是一个分布式的数据网格平台,支持内存数据管理、复制、划分、数据识别路由和连续查询。
- Infinispan:Infinispan是一个基于Java的开源键值NoSQL数据存储,和分布式数据节点平台,支持事务,peer-to-peer 及client/server 架构。
- GridGain:分布式、面向对象、基于内存、SQL+NoSQL键值数据库。支持ACID事务。
- GigaSpaces:GigaSpaces内存数据网格能够充当应用的记录系统,并支持各种各样的高速缓存场景。
原文链接: NoSQL Database Adoption Trends

InnoDBBufferPool reduces disk I/O by caching data and indexing pages, improving database performance. Its working principle includes: 1. Data reading: Read data from BufferPool; 2. Data writing: After modifying the data, write to BufferPool and refresh it to disk regularly; 3. Cache management: Use the LRU algorithm to manage cache pages; 4. Reading mechanism: Load adjacent data pages in advance. By sizing the BufferPool and using multiple instances, database performance can be optimized.

Compared with other programming languages, MySQL is mainly used to store and manage data, while other languages such as Python, Java, and C are used for logical processing and application development. MySQL is known for its high performance, scalability and cross-platform support, suitable for data management needs, while other languages have advantages in their respective fields such as data analytics, enterprise applications, and system programming.

MySQL is worth learning because it is a powerful open source database management system suitable for data storage, management and analysis. 1) MySQL is a relational database that uses SQL to operate data and is suitable for structured data management. 2) The SQL language is the key to interacting with MySQL and supports CRUD operations. 3) The working principle of MySQL includes client/server architecture, storage engine and query optimizer. 4) Basic usage includes creating databases and tables, and advanced usage involves joining tables using JOIN. 5) Common errors include syntax errors and permission issues, and debugging skills include checking syntax and using EXPLAIN commands. 6) Performance optimization involves the use of indexes, optimization of SQL statements and regular maintenance of databases.

MySQL is suitable for beginners to learn database skills. 1. Install MySQL server and client tools. 2. Understand basic SQL queries, such as SELECT. 3. Master data operations: create tables, insert, update, and delete data. 4. Learn advanced skills: subquery and window functions. 5. Debugging and optimization: Check syntax, use indexes, avoid SELECT*, and use LIMIT.

MySQL efficiently manages structured data through table structure and SQL query, and implements inter-table relationships through foreign keys. 1. Define the data format and type when creating a table. 2. Use foreign keys to establish relationships between tables. 3. Improve performance through indexing and query optimization. 4. Regularly backup and monitor databases to ensure data security and performance optimization.

MySQL is an open source relational database management system that is widely used in Web development. Its key features include: 1. Supports multiple storage engines, such as InnoDB and MyISAM, suitable for different scenarios; 2. Provides master-slave replication functions to facilitate load balancing and data backup; 3. Improve query efficiency through query optimization and index use.

SQL is used to interact with MySQL database to realize data addition, deletion, modification, inspection and database design. 1) SQL performs data operations through SELECT, INSERT, UPDATE, DELETE statements; 2) Use CREATE, ALTER, DROP statements for database design and management; 3) Complex queries and data analysis are implemented through SQL to improve business decision-making efficiency.

The basic operations of MySQL include creating databases, tables, and using SQL to perform CRUD operations on data. 1. Create a database: CREATEDATABASEmy_first_db; 2. Create a table: CREATETABLEbooks(idINTAUTO_INCREMENTPRIMARYKEY, titleVARCHAR(100)NOTNULL, authorVARCHAR(100)NOTNULL, published_yearINT); 3. Insert data: INSERTINTObooks(title, author, published_year)VA


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