nosql | 易学教程

HBase：基本介绍

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HBase基本介绍简介 : hbase是bigtable的开源java版本。是建立在hdfs之上，提供高可靠性、高性能、列存储、可伸缩、实时读写nosql的数据库系统。它介于nosql和RDBMS之间，仅能通过主键(row key)和主键的range来检索数据，仅支持单行事务(可通过hive支持来实现多表join等复杂操作)。主要用来存储结构化和半结构化的松散数据。 Hbase查询数据功能很简单，不支持join等复杂操作，不支持复杂的事务（行级的事务） Hbase中支持的数据类型：byte[] 与hadoop一样，Hbase目标主要依靠横向扩展，通过不断增加廉价的商用服务器，来增加计算和存储能力。 HBase中的表一般有这样的特点：大：一个表可以有上十亿行，上百万列面向列:面向列(族)的存储和权限控制，列(族)独立检索稀疏:对于为空(null)的列，并不占用存储空间，因此，表可以设计的非常稀疏传统数据表- HBase的发展历程 HBase的原型是Google的BigTable论文，受到了该论文思想的启发，目前作为Hadoop的子项目来开发维护，用于支持结构化的数据存储。官方网站：http://hbase.apache.org 2006年Google发表BigTable白皮书 2006年开始开发HBase 2008 HBase成为了 Hadoop的子项目

Mongoengine PointField gives location object expected, location array not in correct format error

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问题 I have a model as follows: class Station(Document): location = PointField() Trying to write data as follows: station = Station() station.location = { "type": "Point", "coordinates": [ 81.4471435546875, 23.61432859499169 ] } station.save() However this gives the error Could not save document (location object expected, location array not in correct format) Mongoengine documentation says such a dictionary should be OK. What am I missing here? 回答1: I face similar problem once, in my case it

【 Redis 详解】------ 介绍、配置、优化

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文章目录一、了解关系数据库（SQL）和非关系数据库（NoSQL）：（1）关系型数据库（SQL）：（2）非关系型数据库（NoSQL）：（3）非关系型数据库产生的背景：二、Redis 简介：三、安装部署 Redis：（1）安装 redis：（2）redis-cli 远程连接：四、Redis 配置文件：五、Redis 数据库常用命令：（一）常用命令：（二）Redis 多数据操作：六、Redis 持久化：（1）持久化概述：（2）持久化分类：（3）RDB持久化：（4）AOF 持久化：七、Redis 性能管理：（1）内存碎片率：（2）内存使用率：（3）回收 Key：一、了解关系数据库（SQL）和非关系数据库（NoSQL）：（1）关系型数据库（SQL）： 1、一个结构化的数据库，创建在关系模型基础上，一般面向于记录； 2、包括 Oracle 、Mysql 、 SQL Server 、Microsoft Access 、DB2 等。优点： 1、易于维护：都是使用表结构，格式一致； 2、使用方便：SQL语言通用，可用于复杂查询； 3、复杂操作：支持SQL，可用于一个表以及多个表之间非常复杂的查询。缺点： 1、读写性能比较差，尤其是海量数据的高效率读写； 2、固定的表结构，灵活度稍欠； 3、对于高并发读写需求，传统关系型数据库来说，硬盘I

springboot2 log4j 2 配置Mongodb3

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【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 第一步、查看正经的配置保证该有的引入包一致 <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId>  <exclusions> <exclusion> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-logging</artifactId> </exclusion> </exclusions> </dependency>  <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-log4j2</artifactId> </dependency>  <dependency> <groupId>org.mongodb<

How to get doc from couchdb without some fields? using Ektorp if possible

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问题 At first I misunderstood my problem and posted this question : Can someone explain me Cascading and FetchType lazy in Ektorp? What I need to do: I need to save an Entity in couchdb and then have way to read it and potentially ignore some fields. So I came up with this solution: I create a show function that delete fields from an object and then send it back. function(doc, req) { var result = doc; var ignore = JSON.parse(decodeURIComponent(req.query.ignore)); //this is an array of field names

NoSql solution to store 20[TB] of data, as vector/array?

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问题 I need to build a system to efficiently store & maintain a huge amount (20 [TB]) of data (and be able to access it in 'vector' form). Here are my dimensions: (1) time (given as an integer of the form YYYYMMDDHHMMSS) (2) field (a string of any given length, representing a name of a hospital) (3) instrumentID (an integer representing a uniqueID for the instrument) I will need a way to be able to store data individually, meaning, something like: STORE 23789.46 as the data for instrumentID = 5 on

Storing JS arrays and objects in a database

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问题 I have an application that lets users build things in JS. I want the user to be able to save the current state of his work to reuse it or share it, but what he has is a collection of JS objects stored in a JS array, with very different properties (color, label, x/y position, size, etc.). SQL seems terrible for that particular task, forcing me to maintain tables for every different object, and alas I know very little about NoSQL database. What tools would you use to perform this ? MongoDB

Easiest way to import a simple csv file to a graph with OrientDB ETL

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问题 I would like to import a very simple directed graph file in csv to OrientDB. Concretely, the file is the roadNet-PA dataset from the SNAP collection https://snap.stanford.edu/data/roadNet-PA.html. The first lines of the file are as follows: # Directed graph (each unordered pair of nodes is saved once) # Pennsylvania road network # Nodes: 1088092 Edges: 3083796 # FromNodeId ToNodeId 0 1 0 6309 0 6353 1 0 6353 0 6353 6354 There is only one type of vertex (a road intersection) and edges have no

MongoDB full text search and lookup operator [duplicate]

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问题 This question already has an answer here : How to perform a $text search on a 'joined' collection via $lookup? (1 answer) Closed last month . Full text search in MongoDB seems to be a nice feature, especially when it comes to the need of high performance search and indexes. However, I am wondering why a full text search is not allowed over more than one collection. For example: I have a supplier and a products collection (every supplier has n products) I would really like to do a search over

数据库Mongodb

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1.数据库 1.什么是数据库？存储数据的一个仓库 2.数据库的分类？关系型数据库（ SQL ）=>( mysql )和非关系型数据库( NOSQL )=>( Mongodb ) 3.如何区分一个数据库属于哪个类别？看有没有表，有表就是 SQL ，没有就是 NOSQL 4.数据库的构成？关系型数据库数据库 -> 表 -> 行非关系型数据库数据库 -> 集合 -> 文档 2. MongoDB 1.概念基于分布式文件存储的数据库 2.存储类型： BSON bson 是 json 的超集， bson 拥有 json 的所有，但是它有 json 没有的二进制类型 3. MongoDB 操作命令 show dbs 查看数据库列表 use 数据库名称创建或是切换数据库如果这个数据库没有，那么就是创建如果有，那就是切换数据库 db.集合名称[ 复数 ].save() // 创建一个集合，并且往这个集合添加一条数据 db.集合名称[ 复数 ].insert() // 创建一个集合，并且往这个集合添加一条数据 save如果指定主键，那么就是修改 insert指定主键添加，会报错 show collections 查看数据库下有几个集合 db.users.remove({}) 删除数据库 db.users.find() 查找users集合中所有数据 db.users.findOne

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