Demystify Data Backfilling. Let’s talk about data engineers’… | by Xiaoxu Gao | Nov, 2023

Let’s discuss information engineers’ nightmare

As information engineers, we encounter distinctive challenges every single day. But when there’s one daunting activity that stands out, it have to be the backfill. A flawed backfill means extreme processing time, information contamination, and substantial cloud payments. And yeah, it additionally means you want another backfill job to repair it.

Finishing your first profitable information backfill is an information engineering ceremony of passage. — Dagster

Backfill activity calls for a set of information engineering abilities to be successfully completed comparable to area information to validate outcomes, tooling experience to run backfill jobs, and a strong understanding of the database to optimize the method. When all of those components are intertwined inside a single activity, issues can go mistaken.

On this article, we’ll discover the idea of information backfilling, its necessity, and environment friendly implementation strategies. Whether or not you’re a newbie in backfilling or somebody who usually feels panic about such duties, this text will calm your thoughts and aid you regain your confidence.

What’s backfill?

Backfill is the method of filling in lacking information from the previous on a brand new desk that didn’t exist earlier than, or changing previous information with new data. It’s normally not a recurring job and it’s needed just for information pipelines that replace the desk incrementally.

For instance, a desk is partitioned on date column. An everyday day by day job updates simply the newest 2 partitions. In distinction, a backfill job can replace partitions all the best way again to the preliminary one within the desk. If the common job updates all the desk every time, a backfill job turns into pointless because the historic information will naturally be up to date via the common job.

So, when do we have to backfill?

Normally, there are a couple of frequent situations. Let’s see should you discover them acquainted.

• Create a brand new desk and need to fill in lacking historic information