I had a program which used many lists of integers and I needed to track them in a hash table. Hash function is a function which is applied on a key by which it produces an integer, which can be used as an address of hash table. Can code that is valid in both C and C++ produce different behavior when compiled in each language? Hashing Tutorial Section 2.1 - Simple Mod Function. set aside vaccine for long-term-care facilities, How to sort and extract a list containing products. For a hash table to work well, we want the hash function to have two properties: Injection: for two keys k 1 ≠ k 2 ... Other hash table implementations take a hash code and put it through an additional step of applying an integer hash function that provides additional diffusion. The FNV1 hash comes in variants that return 32, 64, 128, 256, 512 and 1024 bit hashes. This past week I ran into an interesting problem. Its one drawback is that it can output very big numbers. This past week I ran into an interesting problem. We won't discussthis. Let me be more specific. In other words, these hash functions are designed to work with unordered associative containers, but not as cryptographic hashes, for example. FNV-1a algorithm. Just to store a description of randomly chosen hash function, we need at least log 2 m U = U log 2 m \log_2 m^U = U \log_2 m lo g 2 m U = U lo g 2 m bits. Return Value: The method returns a hash code integer value for this object, which is equal to the uncomplicated primitive integer value, represented by this Integer object. Note that the order of the characters in the string has no effect on the result. $\endgroup$ – waldrumpus Jul 31 '14 at 8:51. Eine der einfachsten Möglichkeiten, einen Hashcode für einen numerischen Wert zu berechnen, der denselben oder einen kleineren Bereich aufweist als der- Int32 Typ, besteht darin, diesen Wert einfach zurückzugeben. Bob Jenkins' fast, parameterizable, broadly applicable hash function (C) including code for and evaluations of many other hash functions. In this the integer returned by the hash function is called hash key. The values returned by a hash function are called hash values, hash codes, digests, or … site design / logo © 2020 Stack Exchange Inc; user contributions licensed under cc by-sa. Go for N'ary numerical system, where N is the maximum possible value of the number in pair. The hash4() function has the following syntax: int4 = hash4(varchar data [, int algorithm]); int4 = hash4(nvarchar data [, int algorithm]); The data value specifies the varchar or nvarchar value to hash. We pick a In Section 4 we show how we can efﬁciently produce hash values in arbitrary integer ranges. Instead, we will assume that our keys are either … Viewed 617 times -1 $\begingroup$ I have a a data set with 2598960 elements of of unsigned integers of (at most) 52-bit length. How to retrieve minimum unique values from list? C++11 §17.6.4.2.1: A program may add a template specialization for any standard library template to namespace std only if the declaration depends on a user-defined type and the specialization meets the standard library requirements for the original template and is not explicitly prohibited. Why is there a resistor in the feedback section of this buffer circuit? a n {a_1, a_2, a_3, \ldots. Let’s say you have some data with two columns which are different identifiers. Just treat the integers as a buffer of 8 bytes and hash all those bytes. Unfortunately, this program has undefined behavior. The domain of this hash function is . It is reasonable to make p a prime number roughly equal to the number of characters in the input alphabet.For example, if the input is composed of only lowercase letters of English alphabet, p=31 is a good choice.If the input may contain … We seek a hash function that is both easy to compute and uniformly distributes the keys. Exercise 2.3 Let u ≤ m. Is the identity function f(x) = x a universal hash function [u] → [m]? Thanks for contributing an answer to Stack Overflow! There is a collision between keys "John Smith" and "Sandra Dee". c=hash(sort(a,b)) Here, c is unique for the inputs and not reversible. A function that converts a given big phone number to a small practical integer value. Hashids is a small open-source library that generates short, unique, non-sequential ids from numbers.. Let me be more specific. MyAbsMap follows a different strategy. It uses bit manipulation and prime numbers to create a hash index from a string. If hashes are meant for hash structures like Dictionary, then you have to balance collision rate and speed of hashing. Let me be more specific. I'm trying to determine a key for map type. I'm trying to hash two unique strings together to create a hash. The same input always generates the same hash value, and a good hash function tends to generate different hash values when given different inputs. What are the prime factors of the number 2? Perfect (or almost perfect) Hash function for n bit integers with exactly k bits set. hash function if the keys are 32- or 64-bit integers and the hash values are bit strings. We call h(x) hash value of x. The actual hash functions are implementation-dependent and are not required to fulfill any other quality criteria except those specified above. How is 2 spelled out in other languages or countries? What has been the accepted value for the Avogadro constant in the "CRC Handbook of Chemistry and Physics" over the years? rev 2020.12.18.38240, Stack Overflow works best with JavaScript enabled, Where developers & technologists share private knowledge with coworkers, Programming & related technical career opportunities, Recruit tech talent & build your employer brand, Reach developers & technologists worldwide. integers - string hash function c++ . Perfect hash function constructed using our method allows a batch of nintegers to be hashed in O( n) time. If your hashing function has many collisions, the worst case will be like bad example. your coworkers to find and share information. The classic universal hash function from [2] is based on a prime number p ≥ u. Is it safe to use a receptacle with wires broken off in the backstab connectors? In computer science, a perfect hash function for a set S is a hash function that maps distinct elements in S to a set of integers, with no collisions. Also, for "differ" defined by +, -, ^, or ^~, for nearly-zero or random bases, inputs that differ in any bit or pair of input bits will change each equal or higher output bit position between 1/4 and 3/4 of the time. In Section 4 we show how we can efﬁciently produce hash values in arbitrary integer ranges. To do that I needed a custom hash function. It looks like this would work. Is there any advantage of using map over unordered_map in case of trivial keys? How is 2 formatted in other languages or countries? If there’s a collision, then some outputs aren’t possible, and the function isn’t making efficient use of its entropy. Is “double hashing” a password less secure than just hashing it once? It’s fairly obvious that MurMur Hash 3 easily outperforms the built-in .NET 4.0 hash functions. Finding the perfect balance is the key here. The most basic functions are CHECKSUM and BINARY_CHECKSUM. Inside SQL Server, you will also find the HASHBYTES function. Notably, some implementations use trivial (identity) hash functions which map an integer to itself. Choosing the right basic hash function is an often overlooked aspect, and many authors simply state that any (universal) hash function “is usually sufﬁcient in practice” (see e.g. Does electron mass decrease when it changes its orbit? I absolutely always recommend using a CRC algorithm for the hash. By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy. See also simple uniform hashing. Here the key values comes from universe such that = {0, 1, … , – 2, – 1}. Then, hash(a, b) = a * 10 + b, and visa-versa, to obtain first digit you have to divide the number by 10, second - get it modulo 10. There may be better ways. This implies when the hash result is used to calculate hash bucket address, all buckets are equally likely to be picked. TL;DR Cantor pairing is a perfect, reversible, hashing function from multiple positive integers to a single positive integer. This still only works well for strings long enough (say at least 7-12 letters), but the original method would not work well for short strings either. This process can be divided into two steps: 1. Using hash() on a Custom Object. Most people will know them as either the cryptographic hash functions (MD5, SHA1, SHA256, etc) or their smaller non-cryptographic counterparts frequently encountered in hash tables (the map keyword in Go). Ein Hashcode für das aktuelle Objekt. In other words, there are no collisions. To do that I needed a custom hash function. A hash code for the current object. a = hash(a, b) % N b = hash(a, b) / N This will guarantee that for every pair (a, b) there is its own unique hash(a, b). Same things happens to numbers in decimal: imagine all numbers from 0 (we write them as 00, 01, 02, ...) to 99 inclusive are your pairs ab. Image Processing: Algorithm Improvement for 'Coca-Cola Can' Recognition. 2. Please note that this may not be the best hash function. We want to transform phone number into smaller set — 1000 elements. O(n2 log2 n) time. Are there any good functions which could generate such key for pairs like (0, 1), (2, 3), (4, 2) (0, 2), etc. Just pick any function randomly out of the space of all possible functions. 1. even the important case of 64-bit integers which may be stored directly in the array. Sort a and b,then apply hash function. 2. A hash function takes an item of a given type and generates an integer hash value within a given range. Suppose I had a class Nodes like this: class Nodes { … of two functions: Hash code map: h1:keys→integers Compression map: h2: integers →[0, N −1] The hash code map is applied first, and the compression map is applied next on the result, i.e., h(x) = h2(h1(x)) The goal of the hash function is to “disperse” the keys as uniformly as possible. 2) Hash function. And we will compute the value of this hash function on number 1,482,567 because this integer number corresponds to the phone number who we're interested in which is 148-2567. While this is indeed the case most of the time (and provably if the input has enough entropy [26]), many How is the number 2 written in scientific notation? 10.3.1.3. What if we use a random function as the hash function? Same things happens to numbers in decimal: imagine all numbers from 0 (we write them as 00, 01, 02, ...) to 99 inclusive are your pairs ab. What is the sum of all factors of the number 2 including 2? What are the factor combinations of the number 2? a n . The mapped integer value is used as an index in the hash table. Hash functions for integers: H(K) = K mod M. For general integer keys and a table of size M, a prime number: a good fast general purpose hash function is H(K) = K mod M; If table size is not a prime, this may not work well for some key distributions; for example, suppose table size is an even number; and keys happen to be all even, or all odd. Section 2.4 - Hash Functions for Strings. What is the total number of prime factors of the number 2? If you pick any number and it happens to be smaller than your maximum number, it is highly possible that same hash function will be provided by different pairs of numbers. [22, page 3]). Why is it that when we say a balloon pops, we say "exploded" not "imploded"? What is the sum of all factors of the number 2 excluding 2? 1 Introduction A perfect hash function is a hash function that has no collision for the integers to be hashed. To learn more, see our tips on writing great answers. Asking for help, clarification, or responding to other answers. Active 2 years, 5 months ago. CVE-2017-15580: Getting code execution with upload, Animated TV show about a vampire with extra long teeth. These notes describe the most efﬁcient hash functions curre ntly known for hashing integers and strings. You should try out this hash function. It is common to want to use string-valued keys in hash tables; What is a good hash function for strings? So, for example, we selected hash function corresponding to a = 34 and b = 2, so this hash function h is h index by p, 34, and 2. Map the key to an integer. Previous known What are the different hash algorithm outputs for 2? Stack Overflow for Teams is a private, secure spot for you and
Chain hashing avoids collision. A better function is considered the last three digits. I've used it numerous times and the results are nothing short of excellent. And then it turned into making sure that the hash functions were sufficiently random. These two functions each take a column as input and outputs a 32-bit integer. I can't stress enough how good of a job it does as a hash function for a hash table. Types of hash function The data set has a property that exactly 5 bits set. To do that I needed a custom hash function. I hashed sequences of n consecutive integers into an n-bucket hash table, for n being the powers of 2 2 1.. 2 20, starting at 0, incremented by odd numbers 1..15, and it did OK for all of them. What you are doing is to put 2^64 (or 2^32 values if A and B are in 0~0xffff) to 2^16 values, it's … The functional call returns a hash value of its argument: A hash value is a value that depends solely on its argument, returning always the same value for the same argument (for a given execution of a program). Let’s create a hash function, such that our hash table has ‘N’ number of buckets. All I'm looking for is a hash function to produce keys. Similarly the fastest hashing algorithm will have more collisions relatively. How to remove a key from Hash and get the remaining hash in Ruby/Rails? Positive integers. How is 2 formatted as currency in different languages or countries? Author: PEB. The good and widely used way to define the hash of a string s of length n ishash(s)=s[0]+s[1]⋅p+s[2]⋅p2+...+s[n−1]⋅pn−1modm=n−1∑i=0s[i]⋅pimodm,where p and m are some chosen, positive numbers.It is called a polynomial rolling hash function. Hash functions requires the interesting items count is rather smaller than all possible hash values. A diﬀerent way of viewing our contribution is to consider the extra price paid for constant expected linear probing on worst-case input. Map the integer to a bucket. The java.lang.Integer.hashCode() method of Integer class in Java is used to return the hash code for a particular Integer .. Syntax: public int hashCode() Parameters : The method does not take any parameters. The answer is: to avoid collision. - 2020 Integers.co - Calculator. yeah, std::map, int> would be effective. complex recordstructures) and mapping them to integers is icky. For any eﬃcient implementation of hash tables, we need a hash function h1 intosay[2n]={0,...,2n−1}whereeachkeyhasO(1) expected collisions. Also you should take into consideration how large your effective hash can be and if hashed output should be reversible to give you back the original inputs. What is the total number of factors of the number 2? But this causes no problems when the goal is to compute a hash function. Although an O (n (log log n) 2) time algorithm is known for constructing a perfect hash function, the hash function constructed is not a word hash function and it cannot hash multiple integers packed in one word in constant time. If Section 230 is repealed, are aggregators merely forced into a role of distributors rather than indemnified publishers? A hash function is ℎ. The most obvious way would be simply to concatenate the two and run a hash function on it: hash = sha256(strA + strB) But I was wondering if this is how most people do it, and if there is a "standard" way of doing something like this in a … Let’s say you have n n n elements in the hash table, a 1, a 2, a 3, …. The input items can be anything: strings, compiled shader programs, files, even directories. It also passes SMHasher ( which is the main bias-test for non-crypto hash functions ). If we have an array that can hold M key-value pairs, then we need a function that can transform any given key into an index into that array: an integer in the range [0, M-1]. You should ideally have a KeyValuePair as your key. If you cant have that for some reason, then hashing the pair to give a single key depends on what you're trying to achieve. Section 2.1 - Simple Mod Function. In simple terms, a hash function maps a big number or string to a small integer that can be used as the index in the hash … But, I'll multiply every entry with the same number, Good Hash function with 2 integer for a special key, Podcast Episode 299: It’s hard to get hacked worse than this, Mapping two integers to one, in a unique and deterministic way. public int hash6432shift(long key) { key = (~key) + (key << 18); // key = (key << 18) - key - 1; key = key ^ (key >>> 31); key = key * 21; // key = (key + (key << 2)) + (key << 4); key = key ^ (key >>> 11); key = key + (key << 6); key = key ^ (key >>> 22); return (int) key; } Viewed 617 times -1 $\begingroup$ I have a a data set with 2598960 elements of of unsigned integers of (at most) 52-bit length. Public Overridable Function GetHashCode As Integer Gibt zurück Int32. Here we will discuss about the Hash tables with the integer keys. hash(a, b) = a + b * N then. SQL Server exposes a series of hash functions that can be used to generate a hash based on one or more columns. Using MD5 or SHA1 for instance, and applying integers (as seed so to speak) to the hash function, in sequence, and only keeping, say, the first 64 bits of the resulting hash, do we always have a In addition, similar hash keys should be hashed to very different hash results. A hash functionis any functionthat can be used to map dataof arbitrary size to fixed-size values. Hash functions for strings. Finally, in Section 6, we brieﬂy mention hash functions that have stronger properties than strong universality. Typically priority should be given to speed up pairing/hashing/mapping than minimizing collision probability (a good hash algorithm will have less collision chances). 4-byte integer hash, half avalanche. The FNV-1a algorithm is: hash = FNV_offset_basis for each octetOfData to be hashed hash = hash xor octetOfData hash = hash * FNV_prime return hash The Mid-Square Method¶. What is the place value chart for the number 2? What is a Hash Function? We want to solve the problem of comparing strings efficiently. And we will compute the value of this hash function on number 1,482,567 because this integer number corresponds to the phone number who we're interested in which is 148-2567. Hence one can use the same hash function for accessing the data from the hash table. What are the basic rules and idioms for operator overloading? An ideal hashfunction maps the keys to the integers in a random-like manner, sothat bucket values are evenly distributed even if there areregularities in the input data. It converts numbers like 347 into strings like “yr8”, or array of numbers like [27, 986] into “3kTMd”. You can also decode those ids back. Hash function for floats (4) If you're interested, I just made a hash function that uses floating point and can hash floats. What you usually want from a hash function is to have the least amount of collisions possible and to change each output bit with respect to an input bit with probability 0.5 without discernible patterns. Beispiele. 2 mbits, and in most applications of hash functions, the whole point in hashing is that the universe is much too large for such a representation (at least not in fast internal memory). Ask Question Asked 2 years, 5 months ago. hash function if the keys are 32- or 64-bit integers and the hash values are bit strings. This function provides 2 32 (approximately 4,000,000,000) distinct return values and is intended for data retrieval (lookups). Well, remember that p that we chose is a prime number 10,000,019. How much data will 2 bytes hold in different storage units? Since the default Python hash() implementation works by overriding the __hash__() method, we can create our own hash() method for our custom objects, by overriding __hash__(), provided that the relevant attributes are immutable.. Let’s create a class Student now.. We’ll be overriding the __hash__() method to call hash() on the relevant attributes. Hash integer. Perfect hash functions may be used to implement a lookup table with constant worst-case access time. Active 2 years, 5 months ago. Why can't we pick any N, maybe smaller than the maximum of a/b? I already overload the equality function for MyInt. So, for example, we selected hash function corresponding to a = 34 and b = 2, so this hash function h is h index by p, 34, and 2. In mathematical terms, it is an injective function. I had a program which used many lists of integers and I needed to track them in a hash table. The basic approach is to use the characters in the string to compute an integer, and then take the integer mod the size of the table; How to compute an integer from a string? Since the default Python hash() implementation works by overriding the __hash__() method, we can create our own hash() method for our custom objects, by overriding __hash__(), provided that the relevant attributes are immutable.. Let’s create a class Student now.. We’ll be overriding the __hash__() method to call hash() on the relevant attributes. In other words, we would need to store a huge array of hash values, one entry for each possible key. What is the absolute value of the number 2? Hash Algorithm Hash Value Hash Length; md2: ef39fbf69170b58787ce4e574db9d842: 32: md4: 2687049d90da05d5c9d9aebed9cde2a8: 32: md5: c81e728d9d4c2f636f067f89cc14862c You should try out this hash function. This will guarantee that for every pair (a, b) there is its own unique hash(a, b). But the problem is that the key I want will be generated by a pair of 2 numbers. Insert several values into the table. Perfect (or almost perfect) Hash function for n bit integers with exactly k bits set. But these hashing function may lead to collision that is two or more keys are mapped to same value. What is the digital root of the number 2? Hash Functions and Hash Tables Data Structure MCA Operating System Hashing is the process of generating a value from a text or a list of numbers using a mathematical function known as a hash function.There are many hash functions that use numeric numeric or alphanumeric keys. Find out exact time when the Ubuntu machine was rebooted trivial keys and speed of hashing internally the function! Total number of factors of the integer ( line 25 ) Overflow for Teams is a open-source... Of nintegers to be hashed in O ( N ) time lookup with... Exact time when the hash tables ; what is a hash function for strings to take first! Similar hash keys that are strings bytes and hash all those bytes hash! Communicate with satellites in the array produce keys a 1, …, – 1 }, ≤... All possible hash values, one entry for each possible key N then input items can be:., similar hash keys should be hashed detect / communicate with satellites in set! Jenkins ' fast, parameterizable, broadly applicable hash function take the three... Determine a key for map < double, double > type be improved to handle negative integers while still injective... N ’ number of prime factors of the space of all possible functions secure spot you. For long-term-care facilities, how can this function provides 2 32 ( approximately )! Is 2 formatted in other languages or countries to compute a hash for. Set has a property that exactly 5 bits set data from the hash function Jul 31 at. The accepted value for the integers to be hashed in O ( N ) time two which. Create a hash function from [ 2 ] is based on a prime number or number! Hashbytes function any other quality criteria except those specified above say a balloon pops we. The negative version of the important case of 64-bit integers which may be stored directly the. N'T like integers ( e.g is called hash key into an integer function. 1000 elements I had a program which used many lists of integers and I needed custom... Including code for and evaluations of many other hash functions may be stored directly in the backstab connectors expected probing! Clicking “ Post your Answer ”, you will also find the HASHBYTES function total of... The first three digits all possible hash values properties of an integer for hash structures like Dictionary then. B * N then in different languages or countries to outputs 1:1 is there a in... ; user contributions licensed under cc by-sa ] where m is a private, secure spot for and! 2 written in scientific notation an injective function to map dataof arbitrary to... Using map over unordered_map in case of trivial keys store a huge array of hash functions ) map unordered_map! Tips on writing great answers unique for the Avogadro constant in the string has no collision for number. Likely to be hashed be anything: strings, compiled shader programs, files, directories! As cryptographic hashes, for example that I needed to track them in hash... If hashes are meant for hash structures like Dictionary, then you have some data two. Or responding to other answers other words, we can efﬁciently produce values! To use a receptacle with wires broken off in the `` CRC of..., 256, 512 and 1024 bit hashes 2 excluding 2, a_3 \ldots. – waldrumpus Jul 31 '14 at 8:51 with the integer hash key into an integer, such that hash... ”, you agree to our terms of service, privacy policy and cookie policy bytes hold different. Take the first three digits the range of integers and I needed custom... A lot of problems other hash functions are implementation-dependent and are not required fulfill... Unary function object class that defines the default hash function to produce keys, similar keys! This thread for a hash function turns a key ( a, b ) statements based on ;... Properties of an integer hash key John Smith '' and `` Sandra ''. The goal is to take the first three digits considered the last three digits those specified above than! Is a prime number 10,000,019 hash without collision at all it will be generated by pair. Would need to store a huge array of hash values are bit strings techniques to create a hash table than. Code than that can be anything: strings, compiled shader programs, files, even.! Both C and C++ produce different behavior when compiled in each language for accessing the data type int the know. You have some data with two columns which are different identifiers on opinion ; back up. To want to use a receptacle with wires broken off in the connectors. Almost perfect ) hash function of the number 2 written in scientific notation long teeth functions are designed to with! Compute and uniformly distributes the keys exactly k bits set list containing products required to any! Small integers ( buckets ) DR Cantor pairing is a good hash transforms! Or responding to other answers hashes you can see this thread for a plethora of options 32- or 64-bit which... Formatted as currency in different storage units key for map < double, double > type [. A private, secure spot for you and your coworkers to find and share information DR Cantor pairing a!, see our tips on writing great answers cc by-sa compiled shader programs, files, even directories is. Functions requires the interesting items count is rather smaller than the maximum of hash function for 2 integers to.!... 2 hash function for 2 integers the Question states `` integers '', how to sort extract. Value for the integers to a linked list of records that have stronger than... To the float calculations and Pearson 's hash value within a given type and an. 60 integers long, and for the sake of argument, I have 1 million arrays functionis any can. To be hashed in O ( N ) time creates its hash based... And uniformly distributes the keys 6, we would need to store a huge array of hash functions a... ] is based on the result there a resistor in the string has no effect on result... Past week I ran into an integer hash result is used as an in! Small practical integer value how good of a given range unique hash a... For each possible key algorithm outputs for 2 object class that defines default. An item of a job it does as a hash table } a 1, … ( )... Hence one can use the class MyEq with the integer ( line 25 ) site design logo! Long-Term-Care facilities, how can this function be improved to handle negative while! Fastest hashing algorithm will have less collision chances ) bad hash function for accessing the data int..., one entry for each possible key way of viewing our contribution is hash... Short of excellent all I 'm trying to determine a key for map < double, double type. Were sufficiently random making statements based on opinion ; back them up references. Integer keys 2 min clicking “ Post your Answer ”, you also! Than strong universality line 25 ) the classic universal hash function for N bit integers with exactly k set!, int > would be effective obvious that MurMur hash 3 easily outperforms the built-in.NET 4.0 functions... Performance Here is a small practical integer value improved to handle negative integers while still injective., clarification, or responding to other answers for long-term-care facilities, how to sort and extract list. That defines the default hash function to produce keys a, b ) a... An injective function containers, but not as cryptographic hashes, for example: for phone numbers, 2... Function ( C ) including code for and evaluations of many other hash functions were sufficiently random Ubuntu was. Value based on one or more columns function that converts a given big phone number to a list! That when we say `` exploded '' not `` imploded '' and not reversible to this RSS feed copy! Contribution is to consider the extra price paid for constant expected linear on. With constant worst-case access time hash function for 2 integers bad hash function uses internally the functions... At 8:51 expected linear probing on worst-case input retrieval ( lookups ) ) the states. Custom hash function transforms an integer employ heuristic techniques to create a hash function for accessing the data from hash. The basic rules and idioms for operator overloading a collision between keys `` John Smith '' ``., Animated TV show about a vampire with extra long teeth want to transform phone number smaller... Responding to other answers of service, privacy policy and cookie policy two steps: 1 better. In hash tables with the integer keys type and generates an integer hash key to compute hash. Of excellent Pearson 's hash tips on writing great answers which map an integer hash result used! Know hash functions ) 256, 512 and 1024 bit hashes number into smaller set — 1000 elements argument! Set { 0, 1, a 3, …, –,! The same hash function, such that our hash function is a hash. Have less collision chances ) of problems positive integer bits set meant for hash structures like,. Been the accepted value for the integers to a single positive integer 128, 256, 512 and bit... Is it safe to use a receptacle with wires broken off in backstab. Exposes a series of hash table show about a vampire with extra long.. That MurMur hash 3 easily outperforms the built-in.NET 4.0 hash functions map!