.. _2026-04-19-bigquery-nested-field-preview-fix_release:

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2026-04-19 - BigQuery Data Preview Fixed for Nested and Repeated Fields
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Release
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AgileData.io - Preview Works Again: Nested BigQuery Fields No Longer Break Data Preview

Previewing data from BigQuery tables that contain nested or repeated fields (arrays and structs) was randomly failing. This has been fixed — data preview now works reliably for all BigQuery table structures, including complex nested schemas.

BigQuery supports rich data types including ARRAY and STRUCT columns, which are common in event data and JSON-sourced tables. Our preview query was not correctly handling the UNNEST operation required for repeated fields, causing intermittent failures that were difficult to predict. The fix ensures repeated fields are correctly unnested before the preview data is returned.

**What was happening:**

* Data preview for BigQuery tables with repeated (array) fields was randomly failing
* The UNNEST logic for repeated fields had a bug that triggered inconsistently
* Failures appeared random because they depended on the specific field values in the sample data

**What this means for you:**

* Data preview works reliably for all BigQuery tables, including those with nested or array fields
* No more unexplained preview errors when exploring complex BigQuery schemas
* More confidence when reviewing data before building rules or catalog entries

Last Refreshed
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*Doc Refreshed: 2026-04-19*