Fivetran never hard-deletes: filter _fivetran_deleted in every query

TL;DR

When building on Fivetran-synced tables, always filter WHERE fivetrandeleted = FALSE (or fivetranactive = TRUE in history mode) in every downstream query, or deleted rows will pollute aggregates. For GDPR-style hard deletes, add a post-load transformation step.

Steps

1. When building on Fivetran-synced tables, always filter WHERE fivetrandeleted = FALSE (or fivetranactive = TRUE in history mode) in every downstream query, or deleted rows will pollute aggregates. For GDPR-style hard deletes, add a post-load transformation step. Agents that count rows or join Fivetran tables without the deleted filter will produce silently wrong numbers.

When to use

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When not to use

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Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Source: Fivetran docs (deleted source data): Fivetran never hard-deletes in the destination. Deleted source rows are soft-deleted via a fivetrandeleted BOOLEAN column set to TRUE. To actually remove data, run DELETE or DROP in the destination yourself, or write a post-load transformation that deletes where fivetrandeleted = TRUE. In history mode there is no fivetrandeleted column at all; deleted rows are marked with fivetranactive = FALSE and every version is kept.

Verified resolution: When building on Fivetran-synced tables, always filter WHERE fivetrandeleted = FALSE (or fivetranactive = TRUE in history mode) in every downstream query, or deleted rows will pollute aggregates. For GDPR-style hard deletes, add a post-load transformation step. Agents that count rows or join Fivetran tables without the deleted filter will produce silently wrong numbers.

Source URL: https://fivetran.com/docs/destinations/troubleshooting/deleted-source-data