Tom Hall

Minister without Portfolio at The Department Of Binary Affairs

Tom is well known to those that know him well - an occasional mountaineer, part-time cyclist and part-time typer-at-a-computer doing a mix of dev and ops since before DevOps was a thing. At the moment he's interested in generative art, Elixir and Julia and has been a little bit obsessed with using ideas from functional programming and distributed build systems to make data pipelines and ETL workflows better.

Past Activities

Tom Hall
Code Mesh LDN
08 Nov 2019
13.40 - 14.25

Data pipelines à la mode

In all businesses there is some kind of data pipeline, even if it’s powered by humans working off a shared drive somewhere. Lots of places are better than this. They have workflow systems, ETL pipelines, analytics teams, data scientists etc.

But, can they say months later which version of which code running on what data generated insights?

Can they be reproduced?

What if the algorithms change?

Do you go back and re-run everything?

Science itself has a reproducibility problem, but it’s worse in most companies and mistakes can be expensive.

There is a useful subset of data pipelines, let's call them “pure”, that only depend on the data flowing through them. For pure pipelines we can use techniques from distributed build systems to allow us to know what code was used for each step, not lose any previous results as we improve our algorithms and avoid repeating work that has been done already.

This talk contains interesting theory but is resolutely practical and with concrete examples in several languages and distributed computation frameworks.




Introduce a way of thinking about data pipelines that allows you to avoid repeating work and track provenance.


  • Data scientists
  • Anyone running ETL type workloads.