Using LAST_VALUE with STRUCTS

Senior Data Engineer • Contractor / Freelancer • GCP & AWS Certified
Search for a command to run...

Senior Data Engineer • Contractor / Freelancer • GCP & AWS Certified
No comments yet. Be the first to comment.
A focused guide to window functions in BigQuery — cumulative sums, rolling averages, ranking functions, named windows, RANGE frames, and more.
title: "Combining STRUCTs with Window Functions in BigQuery" seoTitle: "Use STRUCTs with LEAD/LAG in BigQuery Window Functions" seoDescription: "Reduce repeated LEAD and LAG window function calls in BigQuery by wrapping multiple attributes into a STR...
Here's a useful Dataform concept: pre_operations and post_operations. As the name implies, these represent a set of actions that run before and after the main operation (table, view, or SQL operations

BigQuery has always been a SQL engine for tabular data. Object tables add an interesting twist to that. Instead of rows containing values, an object table gives you one row per file — pointing at da

Query your data lake with warehouse-grade security and performance — without moving a single file.

Ever run a heavy BigQuery SQL query, processed gigabytes of data — and then accidentally closed the tab or forgot to save the results? 😬 Don't re-run it. Your results are still there. BigQuery automa

You can use query parameters in BigQuery hashtag#SQL (now in the console as well!) — but how are they different from variables, and when should you use each? Both parameters and variables act as place

Even an “empty” STRUCT is still technically something. Not the same as a standalone NULL value.
This is why, if you work with STRUCTs in SQL and try to find the latest non-empty struct using LAST_VALUE(...) IGNORE NULLS, you’ll notice it doesn’t help — because the struct, even when all fields are null, is still considered non-null.
LAST_VALUE only skips rows where the entire expression itself is NULL.
To fix this, we can adjust the logic in one of the following ways:
➡️ Setting the value to NULL when all fields are NULL
➡️ Using TO_JSON_STRING + NULLIF to treat such entries as “null”
➡️ Using REGEXP_CONTAINS (thanks ChatGPT) for more dynamic checks
Alternatively, we can just apply LAST_VALUE separately to each individual field in the struct.
If you're new to STRUCTs, see one of my previous posts.
Found it useful? Check out to my Analytics newsletter at notjustsql.com.
Enjoyed this? Here are some related articles you might find useful: