MongoDB学习笔记

这是我阅读《MongoDB权威指南》的学习笔记，前七章侧重在开发者角度谈MongoDB,后面才是运维管理者角度

一. 理论部分

入门

文档：多个键及其关联的值有序地放置在一起便是文档
集合：一组文档

虽然子集合没有特别的地方，但还是很有用，很多MongoDB工具中都包含子集合

GridFS是一种存储大文件的协议，使用子集合来存储文件的元数据，这样就与内容块分开了
MongoDB的Web控制台通过子集合的方式将数据组织在DBTOP部分
绝大多数驱动程序都提供语法糖，为访问指定集合的子集合提供方便。例如：在数据库shell里面，db.blog代表blog集合，db.blog.posts代表blog.posts集合

在MongoDB中使用子集合来组织数据是很好的方法，在此强烈推荐

数据类型

JSON表现力也有限制，因为只有null,布尔，数字，字符串，数组和对象几种类型，
MongoDB保留JSON键值对基础上，增添了其他一些数据类型

使用GridFS存储文件有如下原因：

会直接利用业已建立的复制或分片机制，所以对于文件存储来说故障恢复和扩展都很容易
可以避免用户上传内容的文件系统出现的某些问题
不产生磁盘碎片，因为MongoDB分配数据文件空间以2GB为一块

开发者角度到此为止，下一篇是运维角度的学习

Interview at the All Things Digital D5 Conference, Steve and Bill Gates spoke with journalists Kara Swisher and Walt Mossberg onstage in May 2007.

Kara Swisher: The first question I was interested in asking is what you think each has contributed to the computer and technology industry— starting with you, Steve, for Bill, and vice versa. Steve Jobs: Well, Bill built the first software company in the industry. And I think he built the first software company before anybody really in our industry knew what a software company was, except for these guys. And that was huge. That was really huge. And the business model that they ended up pursuing turned out to be the one that worked really well for the industry. I think the biggest thing was, Bill was really focused on software before almost anybody else had a clue that it was really the software that— KS: Was important? SJ: That’s what I see. I mean, a lot of other things you could say, but that’s the high-order bit. And I think building a company’s really hard, and it requires your greatest persuasive abilities to hire the best ...

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产品随想 | 周刊第69期：Do not go gentle into that good night

Products Windows Apps That Amaze Us https://amazing-apps.gitbook.io/windows-apps-that-amaze-us/ 令人精细的Windows App 文物出版社 https://book.douban.com/press/2456/ 这是一个宝藏出版社，出品书籍质量非常高，大开眼界 blind https://www.teamblind.com/ 老外的匿名职场社交工具，挺有意思，看看硅谷的meme 中国科学技术大学测速网站 https://test.ustc.edu.cn/ 看着还不错，挺靠谱的底层代码是LibreSpeed https://github.com/librespeed/speedtest 能不能好好说话？ https://github.com/itorr/nbnhhsh 也是我的一个痛点 Tree Style Tab (aka TST) https://github.com/piroor/treestyletab 一个超强的浏览器扩展插件，树状呈现浏览器标签 Failory Pitch Decks https://www.failory.com/pitch-deck 超级多的融资计划投资板，Pitch Book AutoCut https://github.com/mli/autocut 用文本编辑器剪视频全网漫游指南 https://tagly.notion.site/tagly/a333efd8c3e54e12b123acd541e8d3e6 数字时代的指引，希望他们成功 IT eBooks https://it-ebooks.info/ IT书籍下载 ToastFish https://github.com/Uahh/ToastFish 一个利用摸鱼时间背单词的软件。利用Win10通知栏，出现、背单词 Ideas 沈向洋：IDEA 如何找到创新的「甜区」 https://mp.weixin.qq.com/s/OlI5VUxQKU_ijWZClQCG0Q AIGC How Did Nor...

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Commencement Address at Stanford University--“Stay hungry. Stay foolish.”

I am honored to be with you today for your commencement from one of the finest universities in the world. Truth be told— I never graduated from college. This is the closest I’ve ever gotten to a college graduation. Today I want to tell you three stories from my life. That’s it. No big deal. Just three stories. The first story is about connecting the dots. I dropped out of Reed College after the first six months but then stayed around as a drop-in for another eighteen months or so before I really quit. So why did I drop out? It started before I was born. My biological mother was a young, unwed graduate student, and she decided to put me up for adoption. She felt very strongly that I should be adopted by college graduates, so everything was all set for me to be adopted at birth by a lawyer and his wife. Except that when I popped out they decided at the last minute that they really wanted a girl. So my parents, who were on a waiting...

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犀流研习班第十期001-2讲听课笔记

一. 杂谈 1. Max 逼真的效果图和视频 2. SU 显示模式，费力可以作出好看的效果图 3. Maya 支持Nurbs,但不快捷，对CAD导出也不方便

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Interview with Steve Jobs, WGBH, 1990

Interviewer: what is it about this machine? Why is this machine so interesting? Why has it been so influential? Jobs: Ah ahm, I'll give you my point of view on it. I remember reading a magazine article a long time ago ah when I was ah twelve years ago maybe, in I think it was Scientific American . I'm not sure. And the article ahm proposed to measure the efficiency of locomotion for ah lots of species on planet earth to see which species was the most efficient at getting from point A to point B. Ah and they measured the kilocalories that each one expended. So ah they ranked them all and I remember that ahm...ah the Condor, Condor was the most efficient at [CLEARS THROAT] getting from point A to point B. And humankind, the crown of creation came in with a rather unimpressive showing about a third of the way down...

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巴菲特致股东信-1976年

笔记：为什么选择轻资产行业：当竞争疯狂时，不会强迫加入降价大战最终选择了费雪的思想，选择能理解的优秀企业，以合理的价格买入并长期拥有翻译：雪球：https://xueqiu.com/6217262310/131440258 备份：https://archive.ph/XLK0S 原文： To the Stockholders of Berkshire Hathaway Inc, After two dismal years, operating results in 1976 improved significantly. Last year we said the degree of progress in insurance underwriting would determine whether our gain in earnings would be "moderate" or "major." As it turned out, earnings exceeded even the high end of our expectations. In large part, this was due to the outstanding efforts of Phil Liesche's managerial group at National Indemnity Company. In dollar terms, operating earnings came to $16,073,000, or $16.47 per share. While this is a record figure, we consider return on shareholders' equity to be a much more significant yardstick of economic performance. Here our result was 17.3%, moderately above our long-term average and even further above the average o...

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产品随想 | 周刊第90期：史家之绝唱，无韵之离骚

Why AI Will Save the World https://a16z.com/2023/06/06/ai-will-save-the-world/ Marc Andreessen的雄文，十分有說服力，邏輯清晰辯證了現今AI監管拋出的5個可能的AI問題讀的過程中，腦海裏浮現的都是編程隨想那篇文章为什么马克思是错的？——全面批判马列主义的知名著作导读 https://program-think.blogspot.com/2018/09/Book-Review-The-Errors-of-Marxism-Leninism.html 兩者的思維鏈條、敘事方式，非常相似人民聖殿教 https://zh.wikipedia.org/zh-hk/人民圣殿教?useskin=vector 瓊斯自稱是神的化身，幾千年前轉世為釋迦牟尼，創建了佛教；後來又轉世為耶穌基督，創建了基督教；之後短期化身轉世為巴孛，建立巴哈伊信仰；最後轉世為列寧，將社會主義發揚光大。邪教徒聲稱自己轉世成了列寧，這說明了什麼？ Apple Vision https://stratechery.com/2023/apple-vision Omnivore https://github.com/omnivore-app/omnivore Omnivore is a complete, open source read-it-later solution for people who like reading. How the YouTube Algorithm Works in 2023: The Complete Guide https://blog.hootsuite.com/how-the-youtube-algorithm-works/#A_brief_history_of_the_YouTube_algorithm 外人眼中的YouTube推薦算法變遷 Histography https://histography.io/ “Histography" is interactive timeline that spans across 14 billion years of history, f...

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巴菲特致股东信-1973年

笔记：在上一年度预测的今年竞争加剧导致利润下滑，真的发生了翻译Link：雪球：https://xueqiu.com/6217262310/131257618 备份：https://archive.ph/KIfdT 原文： To the Stockholders of Berkshire Hathaway Inc.: Our financial results for 1973 were satisfactory, with operating earnings of $11,930,592, producing a return of 17.4% on beginning stockholders' equity. Although operating earnings improved from $11.43 to $12.18 per share, earnings on equity decreased from the 19.8% of 1972. This decline occurred because the gain in earnings was not commensurate with the increase in shareholders' investment. We had forecast in last year's report that such a decline was likely. Unfortunately, our forecast proved to be correct. Our textile, banking, and most insurance operations had good years, but certain segments of the insurance business turned in poor results. Overall, our insurance business continues to be a most attractive area in which to employ capital. Management'...

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内网域名访问内网服务器

部门ftp服务器和远程服务器内网域名无法访问问题困扰我好久，钻研了几天，终于明白了一些，和大家做一个分享，原帖子在这里，表示感谢

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巴菲特致股东信-1974年

笔记：价格战企业的逻辑：需要降价获取销量--->需要降低成本--->怎么降？扩大规模以摊低成本--->提高固定资产投入--->净资产回报率会降低翻译：雪球：https://xueqiu.com/6217262310/131257947 备份：https://archive.ph/5CEP6 原文： To the Stockholders of Berkshire Hathaway Inc.: Operating results for 1974 overall were unsatisfactory due to the poor performance of our insurance business. In last year's annual report some decline in profitability was predicted but the extent of this decline, which accelerated during the year, was a surprise. Operating earnings for 1974 were $8,383,576, or $8.56 per share, for a return on beginning shareholders' equity of 10.3%. This is the lowest return on equity realized since 1970. Our textile division and our bank both performed very well, turning in improved results against the already good figures of 1973. However, insurance underwriting, which has been mentioned in the last several annual reports as running at levels of unsustainable profitability, turned dramatically worse...

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