## kdb programming challenge – self similarity

A self similar object is one that is exactly or approximately similar to a part of itself (i.e. the whole has the same shape as one or more of the parts). Self similarity is a central property of fractals. Many objects in the real world, such as coastlines, are statistically self-similar: parts of them show the same statistical properties at …

kdb programming challenge – self similarity

## Supporting kdb+ Tick

Many financial institutions use kdb+ tick to capture and store market data. The same technology stack can be used to capture, store and analyse other forms of real time streaming data including sensor data from manufacturing production lines, usage data from utility smart meters, or telemetry data from Formula 1 cars. At AquaQ we provide onsite and nearshore 24/7 support …

Supporting kdb+ Tick

## Garbage Collection in kdb+

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 …

Garbage Collection in kdb+

## kdb programming challenge – square-free sequences

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. …

kdb programming challenge – square-free sequences

## kdb programming challenge – number bases

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 …

kdb programming challenge – number bases

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

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 …

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

## kdb programming challenge – countdown numbers game

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 …

kdb programming challenge – countdown numbers game

## kdb programming challenge – rotating substitution cipher

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 …

kdb programming challenge – rotating substitution cipher