Garbage Collection in kdb+

AquaQ Admin kdb, kdb+ 6 Comments

The aim of this article is give an understanding of how kdb+ uses and releases memory, and the options available to modify the behaviour. kdb+ allocates memory in powers of 2.  A vector of data will always be placed into a memory block which is the next power of two up from the raw data size (and allowing for some …

AquaQ AdminGarbage Collection in kdb+

kdb programming challenge – square-free sequences

Matt Doherty kdb+ 12 Comments

Continuing on from the number base challenge, this time around we will be looking at square-free sequences. Although they might seem a little disconnected right now, trust me there is a theme to these challenges; all will become clear in time!     In combinatorics a square-free word is any word which does not contain any subword twice in row. …

Matt Dohertykdb programming challenge – square-free sequences

kdb programming challenge – number bases

Matt Doherty kdb+ 10 Comments

In systems of numbers the radix or base is the number of unique digits or symbols that are used to represent numbers. By far the most well known and widely used is the decimal system, which uses the ten digits from 0 through 9 (largely because – much to William Shatner’s surprise – we have 10 fingers). Some other handy …

Matt Dohertykdb programming challenge – number bases

Passwords are better with salt – hashing, salting and key stretching in kdb+

AquaQ Admin kdb+ 1 Comment

Previously we have looked at substitution ciphers in q. Here hashing algorithms will be examined and how their use can help ensure password security. Password security is often a weak link in hardening systems against intrusion, as can be seen by the many reports of high profile breaches, e.g. linkedin  and sony. With 32-bit kdb+ now free for commercial or …

AquaQ AdminPasswords are better with salt – hashing, salting and key stretching in kdb+

kdb programming challenge – countdown numbers game

Matt Doherty kdb+ 2 Comments

This weeks challenge is in honour of the the late Richard Whiteley, who in his time clocked up more hours on British TV screens than anyone else alive! Consonant please, Carol… Puzzle 4 – Countdown Numbers Game The challenge is based on the countdown numbers game and is a little more difficult than previous weeks, so we’ve split it into …

Matt Dohertykdb programming challenge – countdown numbers game

kdb programming challenge – rotating substitution cipher

Matt Doherty kdb+ 4 Comments

Puzzle 3 – Rotating Substitution Cipher In cryptography one of the simplest forms of encryption is the substitution cipher, where you take each letter and pick a replacement for it. Encryption is then as simple as substituting each letter in your message with the replacement letter from the cipher. This type of encryption is usually not difficult to break, since …

Matt Dohertykdb programming challenge – rotating substitution cipher

WebSockets, HTML5 and kdb+

Glen Smith kdb+ 6 Comments

The aim of this post is to introduce the idea of using HTML5 and kdb+ together. HTML is a markup language used to build web pages and HTML5 is the latest version. It comes with many new features but one we will focus on is WebSockets which allows us to easily send and receive data from kdb+. WebSockets allows web …

Glen SmithWebSockets, HTML5 and kdb+

q programming challenge – Narcissistic Numbers

Jamie Grant kdb+ 6 Comments

This is the second in an occasional series of q challenges we’ll post on the blog. Please get involved by posting your own solutions in the comments (prior to revealing the solution). As we get through the backlog of challenges that have been posed and completed by the AquaQ team, future challenges will be conducted ‘live’ on the blog, with …

Jamie Grantq programming challenge – Narcissistic Numbers

kdb programming challenge – Pascal’s Triangle

Matt Doherty kdb+ 8 Comments

Hello and welcome to the hotly anticipated inaugural post of the AquaQ Analytics q programming challenge blog! Hopefully our humble website can handle the inevitable onslaught of puzzle-solving traffic. In this blog we will try to keep you entertained with a series of interesting computational or mathematical problems, and their solutions in kdb+/q. The solutions will be initially hidden for …

Matt Dohertykdb programming challenge – Pascal’s Triangle