## Query redaction for Microsoft SQL Server

URL: https://docs.atlan.com/apps/connectors/database/microsoft-sql-server/references/query-redaction

> Reference for Redact SQL Text on Microsoft SQL Server crawler and miner workflows: what Atlan redacts, what it preserves, and limitations to plan for.

By default, Atlan stores the SQL text it extracts from Microsoft SQL Server exactly as written at source. That text can contain literal values from your business data, such as email addresses in a `WHERE` clause or account numbers in a view definition.

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 per workflow using the _Redact SQL Text_ option.

## Enable redaction

_Redact SQL Text_ is a separate option on each workflow, so you can enable it for the crawler, the miner, or both. The miner doesn't inherit the crawler's setting, so enable it on each workflow whose SQL text you want redacted.

| Workflow | Where to find it |
| --- | --- |
| [Microsoft SQL Server crawler](https://docs.atlan.com/llms/connectors/microsoft-sql-server/crawl-microsoft-sql-server/llms.txt) | _Configure crawler_ screen |
| [Microsoft SQL Server miner](https://docs.atlan.com/llms/connectors/microsoft-sql-server/mine-microsoft-sql-server/llms.txt) | _Configure miner_ screen |

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 for each workflow.

| Workflow | Redacted content |
| --- | --- |
| Crawler | View definitions and the definitions of stored procedures and functions |
| Miner | Query text from SQL Server Query Store |

Within that 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 `TOP` 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 query extracted by the miner:

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

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

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

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.
* `TOP 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.
* `analytics.dbo.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:

* Table-level and column-level lineage.
* Asset names, hierarchy, or any other extracted metadata.

## Limitations

**Earlier miner runs stay unredacted.** SQL text already stored in Atlan from earlier miner runs stays unredacted.

**SQL that Atlan can't parse is stored unredacted.** When parsing fails, Atlan stores the original statement instead of dropping it. Dynamic SQL built with `EXEC` or `sp_executesql`, and procedure bodies that use syntax the parser doesn't support, are the most common cases.

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

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

## See also

* [Crawl Microsoft SQL Server](https://docs.atlan.com/llms/connectors/microsoft-sql-server/crawl-microsoft-sql-server/llms.txt): configure and run the Microsoft SQL Server crawler.
* [Mine Microsoft SQL Server](https://docs.atlan.com/llms/connectors/microsoft-sql-server/mine-microsoft-sql-server/llms.txt): configure and run the Microsoft SQL Server miner.
* [What does Atlan crawl from Microsoft SQL Server?](https://docs.atlan.com/llms/connectors/microsoft-sql-server/what-does-atlan-crawl-from-microsoft-sql-server/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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