SiwenZhang / q_practice

Introduction to Q, the scripting language for KDB+ databases.

q_practice

Join the continuum.

abstract

Example scripts written in q, the query language for kdb+ databases.

basics

1. Clone this repo or use it as a template.
2. Open a terminal and cd to this folder.
3. Start q and enter \l src/init.q to load src/init.q.

contents

src/init.q

Comments, lists, symbols, functions, show, delete, each, 0N!, ?.

src/functions.q

Functions, iterators, lambdas, projections, dot apply, etc.

src/normrand.q

Pseudorandom normal samples with a Box-Muller transform similar to qtips/stat.q.

src/system.q

System commmands, navigation, file handles, current time.

src/tables.q

Example dictionaries, tables, and keys.

test/all

One script to run them all and to test/output write them.

dependencies

• q 3.4+ 64-bit or 32-bit version

examples

Create an alias in a startup file to run q with rlwrap.

export QARCH='m32'
export QHOME="$HOME/q"
alias q='rlwrap --complete-filenames --remember "$QHOME/$QARCH/q"'

Run a q script and interact with it.

q src/tables.q

Run a q script and close the interpreter.

q src/tables.q < /dev/null

Run a q script and save [STDOUT] to a file.

q src/init.q > test/output/init.txt

faq

Where else can I find Q tutorials?

• Kx reference card
• Kx list of repos
• Q Tips

WTF are all these cryptic type values?

I never remember them, so I made a table of datatypes.