access-policy-restrictions.md
The following limitations apply to access policies:
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A column can have only one access policy.
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Column access policies cannot be set on columns of complex types other than native arrays.
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Column access policies cannot be set for materialized columns on flex tables. While it is possible to set an access policy for the
__raw__
column, doing so restricts access to the whole table. -
Row access policies are invalid on temporary tables and tables with aggregate projections.
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Access policy expressions cannot contain:
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Subqueries
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Aggregate functions
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Analytic functions
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User-defined transform functions (UDTF)
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If the query optimizer cannot replace a deterministic expression that involves only constants with their computed values, it blocks all DML operations such as INSERT.