weixin_41365236的博客

原创 【GO】Fan-in, Fan-out

Generator aka IteratorGenerator Pattern is used to generate a sequence of values which is used to produce some output. This pattern is widely used to introduce parallelism into loops. This allows the consumer of the data produced by the generator to r

原创 Tries

The pattern matching algorithms presented in the previous section speed up the search in a text by preprocessing the pattern (to compute the failure function in the KMP algorithm or the last function in the BM algorithm).In this section, we take a complem

原创 The Parallelism Operator (aka Exchange)

The Parallelism Operator (aka Exchange)

原创 Index scan, B+Tree search, (non-)selective predicates

原创 Heap files, row identifiers (RIDs)

原创 OOP-类间的逻辑关系

吉林大学陈伟-面向对象程序设计(基于C++语言讲解) 从面向对象OOP技术的角度来看软件应用系统中的各个程序类之间一般会存在有如下的几种形式的关系：关联（Association）依赖（Dependency）聚合（Aggregation）组合（Composition）泛化（Generalization）水平方向的这种逻辑关系（关联、依赖）在实际的程序中应...

原创 Scan sharing

IBMScan sharing refers to the ability of one scan to exploit the work done by another scan. Examples of shared work include disk page reads, disk seeks, buffer pool content reuse, decompression, and so on.Heavy scans, such as table scans or multidimensio

原创 Bookings Schema Diagram

来源The main entity is a booking (bookings).One booking can include several passengers, with a separate ticket (tickets) issued to each passenger. A ticket has a unique number and includes information about the passenger. As such, the passenger is not a s

原创 Prep quiz: the C programming language

#1 What is the output of the following code snippet? uint32_t v = 0xdeadbeef; printf("%02x", ((unsigned char *) &v)[0]);1) de2) ad3) be4) ef5) 00> ANSWER:#2 What is the output of the following code snippet? int64_t v = 0xdead

原创 what‘s role of VersionSet Version VersionEdit in leveldb?

Note that these are internal types and only people needing to understand the implementation really need to understand these types. But some people like to do so, so here is a brief overview:A Version is a configuration of on-disk files that (in conjunctio

原创 Join trees, join orders, dynamic programming

canonical: 经典的; (数学表达式)最简洁的;residual: 剩余的prune：剪枝; 裁减; 精简;

原创 哈工大数据库PPT

在select迭代器基础之上，构造投影运算的迭代器。反映了一种流水线的工作方式。反映了程序构造的一种思路。例子：输出集合满了！将上述过程按平面给展开：...

原创 Volcano iterator model

Vectorized and Compiled Queries — Part 1Imagine a volcano it is like a cone or at least it is drawn like that by most kids including me ????. The below one is definitely not drawn by a kid.As the shape of the volcano suggests lava(把岩浆比作data) is too much

原创 前缀和专题

https://chengzhaoxi.xyz/25169.html本文总结了力扣上 2000 题以内的关于前缀和的 44 道题，思路接近的题放到了一起。刷完这份题目列表，力扣范围内的前缀和问题可以说刷爆了。基础前缀和区域和检索 - 数组不可变, 题解二维区域和检索 - 矩阵不可变, 题解频数前缀和构建回文串检测, 题解向下取整数对和, 题解数据结构维护前缀和单调队列维护最大子序和, 题解环形子数组的最大和, 题解单调栈维护表现良好的最长时间段, 题解HashMa

原创 由数据范围反推算法复杂度以及算法内容

原创 Map数据结构复习

MapEntries and the Composition PatternAs mentioned above, a map stores key-value pairs, called entries. An entry is actually an example of a more general object-oriented design pattern, the composition pattern, which defines a single object that is comp

原创 Priority Queue

Keys, Priorities, and Total Order RelationsA priority queue needs a comparison rule that never contradicts itself. In order for a comparison rule, which we denote by ≤, to be robust in this way, it must define a total order relation, which is to say th.

原创 How Polymorphism Works

透过对 C 语言的深入理解，可以更好地揭示更高级语言工作的原理。一个例子是 “面向对象”，我们在 C 里也可以实现：struct foo { int (*bar)(struct foo *this, int a, int b); // 函数指针};void baz() { struct foo *ptr = fetch_object(); ptr->bar(ptr, 3, 4); // 等效于C++: ptr->bar(3, 4)}而 C++ 里的对象，的确也是这样

原创 Catalog: Data-Dictionary Storage

原创 Enabling range-based for loops for custom types

C++11标准对语言引入了许多优秀的、有用的改进。我已经介绍了auto关键字，现在我再来说一下基于范围的for循环。怎样使用？怎样在你自己的类中使用？1. 基于范围的for循环的基本语法现在，几乎每一个语言都能有一个非常方便的实现for循环的方法。C++也有类似的概念；你可以为你的for循环，添加一个container，他就会自动迭代。我们看下面的例子：vector<int> vec;vec.push_back(10);vec.push_back(20);for (int i :

原创 IteratorChain

Class IteratorChain<E>An IteratorChain is an Iterator that wraps a number of Iterators.This class makes multiple iterators look like one to the caller. When any method from the Iterator interface is called, the IteratorChain will delegate（选派某人做某事）

原创 【C/C++】零长度数组

零长度数组

原创 【Go语言】Go的RPC包是Synchronous call还是Asynchronous call？

Package rpc provides access to the exported methods of an object across a network or other I/O connection. A server registers an object, making it visible as a service with the name of the type of the object. After registration, exported methods of the obj

原创 arena

IntroductionMemory allocation scheme is a very important issue when developing efficient infrastructures. Normally, we consume memory either from heap or from stack. Heap is flexible but slow, stack is fast but limited, for example array size must be know

原创 [Go语言] The struct fields can be functions

A structure or struct in Golang is a user-defined type, which allows us to create a group of elements of different types into a single unit. Any real-world entity which has some set of properties or fields can be represented as a struct. As we know that in

原创 【UC berkeley】Raft 细节

原创 C语言复杂定义

C gibberish ↔ English练习：f是一个大小为5的数组，数组的元素类型是指针，指向的是参数为int，返回值为int *的函数declare f as array 5 of pointer to function (int) returning pointer to intint *(*f[5]) (int);返回值为int的函数declare abc as function returning intint abc();大小为3的int型数组，declare a

原创 理解pointer to pointer

【中英字幕】【TED】【Linus Torvalds】The mind behind Linux struct list { int item; struct list *next;};/* delete node containing i from list pointed to by lp */struct list *lp, *prevlp;for(lp = li...

原创 Java I/O 装饰器模式

流（Stream）首先，流是什么？流是个抽象的概念，是对输入输出设备的抽象，Java程序中，对于数据的输入/输出操作都是以“流”的方式进行。设备可以是文件，网络，内存等。流是允许你用相似的方式（作为顺序字节流）对待不同数据源的一种抽象。所有 .NET 流类从 System.IO.Stream 类继承。流可以代表内存缓冲器中的数据、从网络连接获得的数据、从文件获得的或要写入文件的数据。流具有方向性，至于是输入流还是输出流则是一个相对的概念，一般以程序为参考，如果数据的流向是从程序到设备，我们成为输

原创 【概念】SQL Server Clustered Tables vs Heap Tables

对关系型数据库产品（RDBMS）而言，一个重要特性就是：数据信息都被组织为二维数据表，信息的表达可以通过一系列的关联（Join）来完成。具体数据库产品在实现这个标准的时候，又有千差万别的特点。就是一个特定的数据库RDBMS产品，往往也提供不同的实现方法。1、从堆表（Heap Table）到索引组织表（Index Organization Table）Oracle作为一款成熟的数据库软件产品，就提供了多种数据表存储结构。我们最常见的就是三种，分别为堆表（Heap Table）、索引组织表（Index Or

原创 mit 6.S081 2020 Lec2 pointer.c

mit6.828 Lec1 pointer.c#include <stdio.h>#include <stdlib.h>void f(void) { // 对于一个数组，我们只能够做两件事： // 1.确定该数组大小[sizeof(数组名)]， // 2.以及获得指向该数组下标为0的元素的指针 /* 数组名：指向该数组下标为0的元素的指针。 数组下标： 任何一个数组下标运算都等同于一个对应的指针运算。 即a[i]=*(