## Query redaction for Tableau

URL: https://docs.atlan.com/apps/connectors/business-intelligence/tableau/references/query-redaction

> Reference for Redact SQL Text on the Tableau crawler workflow: what Atlan redacts, what it preserves, and limitations to plan for.

By default, Atlan stores the custom SQL it extracts from Tableau exactly as written in Tableau. That text can contain literal values from your business data, such as email addresses in a `WHERE` clause or account numbers in a filter.

Query redaction replaces those literal values with placeholders before Atlan stores them. Redaction runs in memory while the workflow extracts data, so the original values aren't written to Atlan's storage or sent outside your environment. Query structure, table references, and column references are preserved, so lineage is unaffected.

Redaction is off by default. You opt in using the _Redact SQL Text_ option on the crawler.

## Enable redaction

| Workflow | Where to find it |
| --- | --- |
| [Tableau crawler](https://docs.atlan.com/llms/connectors/tableau/crawl-tableau/llms.txt) | _Advanced_ page |

The option appears for both direct and Self-Deployed Runtime extraction. With Self-Deployed Runtime extraction, redaction runs inside your Self-Deployed Runtime.

## What Atlan redacts

Redaction applies to the fields that carry SQL text.

| Source | Redacted content |
| --- | --- |
| Tableau Metadata API | The query of each [custom SQL](https://docs.atlan.com/llms/connectors/tableau/what-does-atlan-crawl-from-tableau/llms.txt) table |
| Downloaded workbook and data source definitions | Custom SQL relations and Initial SQL. Applies only when _Download Workbook and Data Source Definitions_ is also enabled. |

Within the redacted text, Atlan replaces:

* **String literals** with `''`.
* **Numeric literals** with `1`. Atlan substitutes a valid number rather than a text placeholder so that the redacted SQL remains parseable.

Atlan also removes comments from redacted SQL and reformats the statement, so stored text won't match the original layout.

### Values Atlan preserves

Some literals are safe to keep and can break the SQL if replaced, so redaction preserves them:

* Date and time literals, such as `'2026-01-01'` or `'2026-01-01 14:30:00'`.
* Month and weekday names, and date part keywords such as `MONTH` or `QUARTER`.
* Currency codes, such as `'USD'`.
* Boolean words: `TRUE`, `FALSE`, `YES`, and `NO`.
* Numbers in structural positions, such as the row count in a `LIMIT` clause, where the value controls the shape of the result rather than describing your data.

Everything else is treated as potentially sensitive and redacted.

## Before and after

A custom SQL query on a Google BigQuery connection:

```sql
-- monthly EMEA revenue check
select order_id, customer_email
from `my-project.analytics.orders`
where region = 'EMEA' and order_total > 500.75
 and created_at >= '2026-01-01' and currency = 'USD'
limit 100;
```

The same query as Atlan stores it with _Redact SQL Text_ enabled:

```sql
/* redacted: true, hash: <original_hash>, redacted_hash: <redacted_hash> */
SELECT
 order_id,
 customer_email
FROM `my-project.analytics.orders`
WHERE
 region = ''
 AND order_total > 1
 AND created_at >= '2026-01-01'
 AND currency = 'USD'
LIMIT 100
```

Note the following:

* `'EMEA'` was replaced, while the date and the currency code were preserved.
* `500.75` became `1`. Redaction indicates that a number was present, not what it was.
* `LIMIT 100` was preserved, because the number controls the result size rather than describing your data.
* The comment was removed and the statement was reformatted.
* Atlan adds a header comment recording that the text was redacted, along with fingerprints of the original and redacted statements. The fingerprint values differ for every statement.
* `my-project.analytics.orders`, `order_id`, and `customer_email` are unchanged, which is why lineage still resolves.

## What redaction preserves

Redaction only changes literal values. Because everything Atlan uses to build relationships stays intact, enabling redaction doesn't change:

* Lineage from custom SQL to upstream tables and columns.
* Asset names, hierarchy, or any other extracted metadata.

## Limitations

**SQL that Atlan can't parse is stored unredacted.** When parsing fails, Atlan stores the original query under a `redacted: false` header instead of dropping it. A downloaded definition that Atlan can't redact is stored as downloaded.

**Redaction increases workflow runtime.** Expect crawler runs to take longer, and account for this if the crawler already runs close to its schedule interval.

**Enabling redaction rewrites stored SQL.** Because the stored text changes for every custom SQL table, the first run after you enable the option updates SQL text across the connection.

## See also

* [Crawl Tableau](https://docs.atlan.com/llms/connectors/tableau/crawl-tableau/llms.txt): configure and run the Tableau crawler.
* [What does Atlan crawl from Tableau?](https://docs.atlan.com/llms/connectors/tableau/what-does-atlan-crawl-from-tableau/llms.txt): assets and metadata Atlan extracts.
* [Query redaction for Snowflake](https://docs.atlan.com/llms/connectors/snowflake/query-redaction/llms.txt): the same option on Snowflake workflows.

_Last updated: 15 October 2026._

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