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Constantin Lungu

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Data Engineer’s Notes

Null-safe comparison: IS DISTINCT/NOT DISTINCT FROM

I’ve been working for surprisingly long with SQL to have found this only a few days ago. Not long enough I guess 🤓.

May 6

Null-safe comparison: IS DISTINCT/NOT DISTINCT FROM

May 6

Published in
Data Engineer’s Notes

Transforming cumulative sums into monthly values

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

Mar 27

Transforming cumulative sums into monthly values

Mar 27

Published in
Data Engineer’s Notes

A quick walkthrough BigQuery Remote Functions

In a previous post, I mentioned Remote Functions-a powerful way to send data from BigQuery to an external service for processing…

Mar 8

A quick walkthrough BigQuery Remote Functions

Mar 8

Published in
Data Engineer’s Notes

Change history in BigQuery

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

Mar 6

Change history in BigQuery

Mar 6

Published in
Data Engineer’s Notes

A quick overview of BigQuery functions

When we talk about functions in BigQuery, we’re referring to several distinct capabilities.

Mar 2

A quick overview of BigQuery functions

Mar 2

Published in
Data Engineer’s Notes

Expressing multiple repeated joins as a correlated subquery

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

Feb 23

Expressing multiple repeated joins as a correlated subquery

Feb 23

Published in
Data Engineer’s Notes

Revisiting GROUP BY ROLLUP with a more realistic example

Ever had a random piece of knowledge from school suddenly click in a real-world scenario?

Feb 22

Revisiting GROUP BY ROLLUP with a more realistic example

Feb 22

Published in
Data Engineer’s Notes

Revisiting Why SQL’s Order of Execution Matters

A few days ago I thought that the following SQL query would not work- I expected the window function result would be summed multiple times.

Feb 21

Revisiting Why SQL’s Order of Execution Matters

Feb 21

Published in
Data Engineer’s Notes

Exploring the BigQuery Query History

Here’s a BigQuery trick I use all the time-seriously, not saying this to make my post catchier 😁.

Feb 19

Exploring the BigQuery Query History

Feb 19

Published in
Data Engineer’s Notes

How ARRAY() can function as UNPIVOT and UNNEST as PIVOT?

I’ve come across this SQL transformation multiple times, and it’s an interesting two-way problem.

Feb 13

How ARRAY() can function as UNPIVOT and UNNEST as PIVOT?

Feb 13

Constantin Lungu

Constantin Lungu

Software Engineer with a focus on Analytics — Data Engineering, Data Science & Business Intelligence | Opinions are my own

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