1. recursive (divide and conquer) divide into smaller problem of same type (have a base condition) combine the result(optional) 1 2 3 4 5 6 7 8 9 10 func recursion(n int){ // exit if n == 1 { return n } // divide into smaller problem; return n + recursion(n-1) } algorithm 1. divide and conquer divide the problem into sub-problems,conquer the problems combine the result;(this step may not be necessay ) 1.
m family m1: mx pro, max: 专业级的芯片
m2 pro vs m1pro
7 Tips to Help You in Your Decision-Making Process
ask the right questions
What are my options? What are the pros and cons of each outcome of this decision? How can I handle each outcome? How can I cope if the decision backfires? What am I giving up by making this decision? Will this decision impact my psychological well-being? How will this decision impact the people around me? What if I fail?
What’s the Diff: VMs vs Containers
Virtualization
虚拟化技术概念学习总结
Docker 核心技术与实现原理
深入分析 Docker 镜像原理
深入分析 Docker 镜像原理
virtualization what: 将硬件资源重新分配， 将一套硬件资源虚拟成多套硬件资源 , 从而运行多个不同的操作系统
涉及的技术:
resource managent: 分配硬件资源 isolation: 隔离多个操作系统 ….. types:
硬件虚拟化(hardware): hypervisor完成虚拟化 操作系统虚拟化(OS-level virtualization ): os 完成虚拟化 images: differ:
虚拟的软件:
hypervior os isolation level:
os level process level docker: 基于linux实现
namespace隔离 进程，文件系统，网络 CGroups 隔离硬件资源(cpu,ram) docker docker package your application and all its dependencyies((including os)) together in a form of container so as to ensure that your application work seamlessly in any envirorment;
Text analysis
what is es a distrubuted document store;
basic concept 1. score In general, scoring in Elasticsearch is a process to determine the relevance of retrieved documents based on user queries, term frequencies, and other important parameters
1. index as a noun: index is the collections of document
as a verb the process of putting the document in the index
2. document the collection of fields ;
3. shared index are divided into mutiple shared;
MySQL中IS NULL、IS NOT NULL、!=不能用索引？胡扯！ - 掘金 - https://juejin.cn/post/6844903921450745863
InnoDB索引允许NULL对性能有影响吗-腾讯云开发者社区-腾讯云 - https://cloud.tencent.com/developer/article/1658064
InnoDB索引允许NULL对性能有影响吗-腾讯云开发者社区-腾讯云 - https://cloud.tencent.com/developer/article/1658064
null value：
没有该属性 有该属性，但是暂时不知道 feature: 基于null 的比较和运算结果都是null
1 2 select null = null // null select 100 + null// null the cons and pros of using null
the cons: 性能开销
增加存储空间,需要使用 额外一个bit 记录是否为null，但是使用非null默认值如0, “",占用空间有时候反而更大 索引失效: 并不会使得索引失效 使用开销: 不方便查询，特别是聚合查询，没有加 is null,not null 可能会导致查询结果失准 1 2 3 4 5 6 7 8 9 10 11 12 // wrong select coutn(name) from person // right select count(*) from person // wronng select * from person where name!
