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Query redaction for Looker

TL;DR

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

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By default, Atlan stores the SQL text it extracts from Looker exactly as Looker generates or defines it. That text can contain literal values from your business data, such as email addresses in a WHERE clause or account numbers in a derived table.

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​

WorkflowWhere to find it
Looker crawlerConfigure crawler screen, after Exclude Projects

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.

SourceRedacted content
QueriesThe SQL Looker generates for the queries behind dashboard tiles and looks
LookML viewsDerived table SQL (derived_table: sql)
LookML views and exploressql_table_name, when it contains a SELECT statement

Within the redacted text, Atlan replaces:

  • String literals with '<REDACTED:STRING>'.
  • 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​

SQL that Looker generates for a tile query on a Google BigQuery connection:

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:

/* redacted: true, hash: <original_hash>, redacted_hash: <redacted_hash> */
SELECT
  order_id,
  customer_email
FROM `my-project.analytics.orders`
WHERE
  region = '<REDACTED:STRING>'
  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 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 Looker assets to upstream tables.
  • 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 statement under a redacted: false header instead of dropping it. Derived table SQL that uses Liquid templating ({% %}, {{ }}) or LookML substitution (${...}) is the most common case.

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 asset with SQL, the first run after you enable the option updates SQL text across the connection.

See also​