17年的旧文,最近因为SageDB论文而重读. 文章主要思路是通过学习key的顺序.结构等来预测record在位置.存在与否等.效果方面,据称部分场景下,相对b-tree可以优化70%的内存占用. 最大价值其实在于使用ML来优化(索引)系统这个新的方向. Range Index 审视下btree查找完成的功能:输入一个key,每次选出一个可能的范围(分支节点),直到最后命中(叶子节点).这其实跟ML中模型类似. 换句话说,若能估算出数据的累积分布(记作F),那么查询key所在位置,也可以看成是…

从AutoML.机器学习新算法.底层计算.对抗性攻击.模型应用与底层理解,到开源数据集.Tensorflow和TPU,Google Brain 负责人Jeff Dean发长文来总结他们2017年所做的工作.但写了一天,Jeff Dean也没覆盖到Google Brain在医疗健康.机器人.基础科学等领域的研究,他接下来打算把如何促进人类创造性.公平和包容性也写进去. 接下来的事情我们接下来再关心,眼下我们还是更关心Jeff Dean已经写好的机器学习技术总结,[AI科技大本营]翻译如下: 核心研…

AI-Sys Syllabus Projects Grading AI-Sys Spring 2019 When: Mondays and Wednesdays from 9:30 to 11:00 Where: Soda 405 Instructors: Ion Stoica and Joseph E. Gonzalez Announcements: Piazza Sign-up to Present: Google Spreadsheet Project Ideas: Google Spre…

官网对skip index scan的解释: Index skip scans improve index scans by nonprefix columns since it is often faster to scan index blocks than scanning table data blocks. In this case a composite index is split logically into smaller subindexes. The number of l…

什么时候需要重建索引 1. 删除的空间没有重用,导致 索引出现碎片 2. 删除大量的表数据后,空间没有重用,导致 索引"虚高" 3.索引的 clustering_facto 和表不一致 也有人认为当索引树高度超过4的时候需要进行重建,但是如果表数量级较大,自然就不会有较高的树,而且重建不会改变索引树高度,除非是由于大量引起的索引树“虚高”,重建才会改善性能,当然这又回到了索引碎片的问题上了. 关于索引是否需要重建,Oracle有这么一句话: Generally speaking, th…

最近研究内存关系数据库的设计与实现,下面一篇为berkeley db原始两位作为的Berkeley DB设计回忆录: Conway's Law states that a design reflects the structure of the organization that produced it. Stretching that a bit, we might anticipate that a software artifact designed and initially produ…

Reference: http://blogs.msdn.com/b/felixmar/archive/2011/02/14/partitioning-amp-archiving-tables-in-sql-server-part-1-the-basics.aspx Database partitioning is a feature available in SQL Server(version 2005 and Up) which lets you split a table among m…

引用自:http://rusanu.com/2013/08/01/understanding-how-sql-server-executes-a-query/ Understanding how SQL Server executes a query August 1st, 2013 If you are a developer writing applications that use SQL Server and you are wondering what exactly happens…

B-tree B-tree is a tree data structure that keeps data sorted and allows searches, sequential access, insertions, and deletions in logarithmic time. B-trees are balanced search trees: height for the worst case, where t >2 is the order of tree, i.e.,…

本章导读 机器学习(machine learning, ML)是一门涉及概率论.统计学.逼近论.凸分析.算法复杂度理论等多领域的交叉学科.ML专注于研究计算机模拟或实现人类的学习行为,以获取新知识.新技能,并重组已学习的知识结构使之不断改善自身. MLlib是Spark提供的可扩展的机器学习库.MLlib已经集成了大量机器学习的算法,由于MLlib涉及的算法众多,笔者只对部分算法进行了分析,其余算法只是简单列出公式,读者如果想要对公式进行推理,需要自己寻找有关概率论.数理统计.数理分析等方面的专…

/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You u…

原文地址:https://stackoverflow.com/questions/47680213/what-are-the-current-differences-between-myisam-and-innodb-storage-engines-speci Your assumption that MyISAM has been receiving new development is not correct. MyISAM is not receiving any significant…

1. Introduction 1.1. About 1.2. Sphinx features 1.3. Where to get Sphinx 1.4. License 1.5. Credits 1.6. History 2. Installation 2.1. Supported systems 2.2. Compiling Sphinx from source 2.2.1. Required tools 2.2.2. Compiling on Linux 2.2.3. Known comp…

Open source software has become a fundamental building block for some of the biggest websites. And as those websites have grown, best practices and guiding principles around their architectures have emerged. This chapter seeks to cover some of the ke…

一.  官方说明 Oracle 11gR2 文档: LOB Storage http://download.oracle.com/docs/cd/E11882_01/appdev.112/e18294/adlob_tables.htm#ADLOB45267 Oracle 10gR2 文档: LOBs in Tables http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14249/adlob_tables.htm#sthref165…

https://www.codeproject.com/Articles/630346/Understanding-how-SQL-Server-executes-a-query https://www.codeproject.com/Articles/732812/How-to-analyse-SQL-Server-performance     This article will help you write better database code and will help you ge…

What does working with large data sets in mySQL teach you ? Of course you have to learn a lot about query optimization, art of building summary tables and tricks of executing queries exactly as you want. I already wrote about development and configur…

14.2 InnoDB Concepts and Architecture 14.2.1 MySQL and the ACID Model 14.2.2 InnoDB Multi-Versioning 14.2.3 InnoDB Redo Log 14.2.4 InnoDB Undo Logs 14.2.5 InnoDB Table and Index Structures 14.2.6 InnoDB Mutex and Read/Write Lock Implementation The in…

转自:http://aosabook.org/en/distsys.html Scalable Web Architecture and Distributed Systems Kate Matsudaira Open source software has become a fundamental building block for someof the biggest websites. And as those websites have grown,best practices and…

1.Data Model Model Is the abstraction of real world Reveal the essence of objects, help people to locate and resolve problems Data Model A data model explicitly determines the structure of data, and defines the operation that can be imposed, in order…

##Advice for Applying Machine Learning Applying machine learning in practice is not always straightforward. In this module, we share best practices for applying machine learning in practice, and discuss the best ways to evaluate performance of the le…

https://docs.bonsai.io/article/123-capacity-planning Capacity Planning Capacity planning is the process of estimating the resources you’ll need over short and medium term timeframes. The result is used to size a cluster and avoid the pitfalls of inad…

Locality sensitive hashing - LSH explained The problem of finding duplicate documents in a list may look like a simple task - use a hash table, and the job is done quickly and the algorithm is fast. However, if we need to find not only exact duplicat…

一.PATHINFO功能简述 搞PHP的都知道ThinkPHP是一个免费开源的轻量级PHP框架,虽说轻量但它的功能却很强大.这也是我接触学习的第一个框架.TP框架中的URL默认模式即是PathInfo模式.这个模式很强大,每当你访问一个网站必然带有一长串参数,但是太长又显得不太友好.对于访问一个以MVC模式搭建的网站,必然带有M.C.A三个参数即module.controller.action,这些参数需要还需要用&符号隔开,假若参数量很多,就显得特别的不友好啦.然而PathInfo模式功能就是…

A peak element is an element that is greater than its neighbors. Given an input array where num[i] ≠ num[i+1], find a peak element and return its index. The array may contain multiple peaks, in that case return the index to any one of the peaks is fi…

一直直到bug-free.不能错任何一点. 思路不清晰:刷两天. 做错了,刷一天. 直到bug-free.高亮,标红. 185,OA(YAMAXUN)--- (1) findFirstDuplicate string in a list of string. import java.util.HashSet; import java.util.Set; public class Solution { public static void main(String[] args) { String[…

1 TextView文本框 1.1 TextView类的结构 TextView 是用于显示字符串的组件,对于用户来说就是屏幕中一块用于显示文本的区域.TextView类的层次关系如下: java.lang.Object   ↳ android.view.View   ↳ android.widget.TextView 直接子类: Button, CheckedTextView, Chronometer, DigitalClock, EditText 间接子类: AutoCompleteTextV…

Problem: A peak element is an element that is greater than its neighbors. Given an input array where num[i] ≠ num[i+1], find a peak element and return its index. The array may contain multiple peaks, in that case return the index to any one of the pe…

平时我们常用的"焦点图/幻灯片""Tab标签切换""图片滚动""无缝滚动"等效果要加载n个插件,又害怕代码冲突又怕不兼容 现在我们只需求要一个多功能前台交互效果插件superSlide就可以搞定了 现在介绍这个插件SuperSlide.2.1.1 下载地址:http://www.superslide2.com/ js.min文件 /*! * SuperSlide v2.1.1 * 轻松解决网站大部分特效展示问题 * 详尽信息请…

A peak element is an element that is greater than its neighbors. Given an input array where num[i] ≠ num[i+1], find a peak element and return its index. The array may contain multiple peaks, in that case return the index to any one of the peaks is fi…