Window Functions, Visualised - Distribution

Let’s look at the window functions cume_dist and ntile, which I’ve dubbed “distribution functions”.

cume_dist

Shortform for cumulative distribution,

percentiles?

ntile

I liken ntile to dividing your window frame equally into “buckets”:

An example:

SELECT
  ntile(3) OVER(ORDER BY cost DESC),
  ...
FROM expenses;

In the above, we’re asking Postgres to divide the frame into 3 buckets:

Following from window functions for rankings

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