hash compressor

Memcache is a distributed cache system, but it does not provide clustering capabilities, which can easily become a bottleneck in large-scale applications. However, the client can be freely extended at this time and implemented in two phases. First phase: Key must first map to a memcache server based on a certain algorithm. The second stage removes the cached value from the server. But there is a problem, such as one of the server hangs, or need to add a service, this time the first phase of the

I. Overview1, our memcache client (here I see the source of Spymemcache), using a consistent hash algorithm Ketama data storage node selection. Unlike the conventional hash algorithm, we only hash the key we want to store the data, and allocate it to different node storage. The consistent hash algorithm computes the

Let's start with a simple question: Have a huge string array, and then give you a separate string that lets you find out if there's a string from this array and find it, what would you do? There is a way to the simplest, honestly from the tail, a comparison, until found, I think as long as the people who have learned the program design can make such a process, but if there are programmers to give such a program to the user, I can only use no language to evaluate, maybe it really can work, but ..

So far, we've introduced sequential lookups, binary lookups, block lookups, and binary sort trees. See the article before the author:http://blog.csdn.net/u010025211/article/details/46635325http://blog.csdn.net/u010025211/article/details/46635183Today's blog post will cover hash lookups.1. Why hashes are used to findThe previous method of finding is required to achieve the ability to find elements and linear tables or elements in a tree.If this time co

1. StatementCryptography is a complex topic and I am not an expert in this field. Many universities and research institutions have long-term research in this area. In this article, I would like to try to show you a secure way to store Web application passwords in a straightforward way. 2. What does "Hash" do?"Hash converts a piece of data (small or large) to a relatively short amount of data, such as a str

1. StatementCryptography is a complex topic and I am not an expert in this field. Many universities and research institutions have long-term research in this area. In this article, I would like to try to show you a secure way to store Web application passwords in a straightforward way. 2. What does "Hash" do?"Hash converts a piece of data (small or large) to a relatively short amount of data, such as a str

Part II: A detailed analysis of the hash table algorithm What is a hash? Hash, the general translation to do "hash", there is a direct transliteration of "hash", is the arbitrary length of the input (also known as pre-mapping, pre-image), through the

In computational theory, there is no hash.Function of the argument, only one-way function of the argument. The so-called one-way function, is a complex definition, you can see the computational theory or cryptography data. WithPeopleClassThe language describes the one-way function: If a function is given input, it is easy to calculate the result, and when the given result is difficult to calculate the input, this is the single function. Various encryption lettersCan be thought of as the approxim

Implementation and Operation of the PHP array Hash table catalogue 1. PHP Hash table 1. PHP array definition1. PHP Hash table 0x1: Basic concepts Hash tables are widely used in practice. for example, the compiler usually maintains a symbol table to store tags. many advanced languages also explicitly support

1. DisclaimerCryptography is a complex topic, and I am not an expert in this field. Many universities and research institutions have long-term research in this area. In this article, I want to try to show you a way to safely store Web program passwords in a way that is easy to understand. 2. What does "Hash" mean?"Hash converts a piece of data (small or big data) into a relatively short amount of data, suc

Common hash FunctionsThe generic hash function library has the following string hashing algorithms that mix addition and one operation. The following algorithms are different in terms of usage and functionality, but can be used as an example to learn the implementation of hashing algorithms. 1.RSobtained from Robert Sedgwicks's algorithms in C book. Some simple optimized algorithms have been added to exp

Hash LookupThe previous lookup algorithm, the time complexity of O (n), or O (㏒2n), its efficiency depends on the number of "comparisons". 即使对于采取排序树结构的查找表，由于每一次比较的结果，如果关键字与数据元素不相等，则有“大于”或者“小于”两个结果，所以下一步会有两种可能的方向，因此O(㏒2n)已经是最优了。Hash table takes another algorithm, the time complexity of finding the fastest can reach O (1), that is, as long as the keyword is given, the element can be found immediately.In pra

Label:SOURCE One Hash index structure of the particularity, its retrieval efficiency is very high, index retrieval can be located at once, unlike B-tree index need from the root node to the side point, and finally access to the page node so many IO access, so the Hash index query efficiency is much higher than the B-tree index. Probably a lot of people have doubts, since the efficiency of the

Hash Table is the core of PHP.PHP arrays, associated arrays, object attributes, function tables, symbol tables, and so on all use HashTable as the container.PHP HashTable adopts the zipper method to solve conflicts. I don't need to mention this. Today I am mainly concerned with the PHP Hash algorithm and some ideas revealed by this algorithm.PHP Hash is currently

Author: vamei Source: http://www.cnblogs.com/vamei welcome reprint, please also keep this statement. Thank you! Hash Hash table)Is from one set a to another set BMapping). Ing isCorrespondenceAnd an element of set a can only correspondOneElement. However, one element in Set B may correspond to elements in multiple set. If the elements in B can only correspond to one element in a, such a ing is called

The following illustrated by the way to show you the PHP kernel exploration: Hash table collision attack principle. The recent hash Table collision Attack (Hashtable collisions as DOS attack) has been the subject of constant mention, and various languages have been recruited. This article unifies the PHP kernel source code, chats this kind of attack the principle and realizes. The basic principle of

1 overview The time efficiency of the list lookup is O (N), and the log2n,b+ tree is log2n by the binary method, but the time efficiency of searching the hash list is O (1). Design efficient algorithms often need to use the hash list, the constant level of the search speed is any other algorithm can not be compared to the structure of the hash table and the diffe

Consistent hashing algorithm from: http://blog.csdn.net/cywosp/article/details/23397179 consistent hashing algorithm a distributed hash (DHT) implementation algorithm, proposed by MIT in 1997, Designed to address hot spot problems in the Internet, the original intention and carp are very similar. The consistent hash corrects the problem caused by the simple hashing algorithm used by carp, so that distribut

Reprint please indicate the source: http://blog.csdn.net/cywosp/article/details/23397179 a distributed hash (DHT) implementation algorithm, proposed by MIT in 1997, Designed to address hot spot problems in the Internet, the original intention and carp are very similar. The consistent hash corrects the problem caused by the simple hashing algorithm used by carp, so that distributed hashing (DHT) can be real

I. Concept A hash table is a structure that stores data in key-value (key-indexed), and we can find its corresponding value simply by entering the value to be looked up as key. The idea of hashing is very simple, if all the keys are integers, then you can use a simple unordered array to implement: The key as an index, the value is its corresponding value, so that you can quickly access the value of any key. This is the case for a simple key, which w