kdb+ and q
Q+A on all things kdb+ database and the q language
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do control word

Can someone please explain how the do control word works in kdb+. I've read the kx wiki about it and still don't understand.

Query Optimization

Hello,Wondering if anyone can help me out on this. I have a user sending a query that's hogging resources. Does anyone know a better way to send this query that would not be as resource intensive.h "select last price by date, sym from trade where dat...

.u.init in tick/u.q

I don't understand how .u.init function works in tick/u.q. Can someone explain how it works ? What is w ? I thought x y and z would be implicit function arguments ? Are there 2 functions declared on line 6 ? The two functions are del and .z.pc ? If t...

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nulls from mdev

When using mdev, I was producing a number of unexpected nulls. It seemsthat the definition is based on sqrt(avg(x^2) - avg(x)) without checkingthat the difference is non-negative before taking the square root.Example:q)5 mdev 10#1e-30 0 0 0 0 0 0 0 0...