Constantin Lungu

Constantin Lungu

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Data Engineer with a passion for transforming complex data landscapes into insightful stories. Here on my blog, I share insights, challenges, and the ever-evolving dance of technology and business.

Transforming cumulative sums into monthly values

Mar 27, 20251 min read

Here’s a quick BigQuery SQL exercise. I often work with cumulative aggregations, but it’s not every day that I need to reverse them—converting...

Transforming cumulative sums into monthly values

A quick walkthrough BigQuery Remote Functions

Mar 8, 20251 min read

In a previous post, I mentioned Remote Functions—a powerful way to send data from BigQuery to an external service for processing, including a Cloud...

A quick walkthrough BigQuery Remote Functions

Change history in BigQuery

Mar 6, 20251 min read

Ever needed to track what changed in a table and when? In data engineering, this is known as Change Data Capture (CDC)—a fundamental challenge when...

Change history in BigQuery

A quick overview of BigQuery functions

Mar 2, 20252 min read

When we talk about functions in BigQuery, we're referring to several distinct capabilities. Beyond the standard built-in functions like...

A quick overview of BigQuery functions

Expressing multiple repeated joins as a correlated subquery

Feb 23, 20251 min read

In yesterday’s post, we looked at retrieving information from a table by joining it multiple times—each with different join criteria. This raises a...

Expressing multiple repeated joins as a correlated subquery

Revisiting GROUP BY ROLLUP with a more realistic example

Feb 22, 20252 min read

Ever had a random piece of knowledge from school suddenly click in a real-world scenario? It felt like that for me remembering about ROLLUP a few days...

Revisiting GROUP BY ROLLUP with a more realistic example