Behavior Change Management¶

Overview¶

Snowflake implements behavior changes monthly in bundles included in regularly-scheduled releases. During the testing period and opt-out period for each behavior change bundle, you can enable or disable the bundle in your account. This document explains how to check whether a particular bundle is enabled in your account and how to enable or disable it.

In this document, bundle_name is the name of the behavior change bundle in the form YYYY_NN, found in the Behavior Change Log.

Checking the Status of a Behavior Change Bundle in Your Account¶

To check whether a specific behavior change bundle is enabled in your account, use the SYSTEM$BEHAVIOR_CHANGE_BUNDLE_STATUS function with the bundle_name as the argument:

SELECT SYSTEM$BEHAVIOR_CHANGE_BUNDLE_STATUS('2021_02');

+-------------------------------------------------+
| SYSTEM$BEHAVIOR_CHANGE_BUNDLE_STATUS('2021_02') |
|-------------------------------------------------|
| DISABLED                                        |
+-------------------------------------------------+

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Enabling a Behavior Change Bundle in Your Account¶

To enable a particular behavior change in your account, use the SYSTEM$ENABLE_BEHAVIOR_CHANGE_BUNDLE function and specify the bundle_name that contains the change:

SELECT SYSTEM$ENABLE_BEHAVIOR_CHANGE_BUNDLE('2021_02');

+-------------------------------------------------+
| SYSTEM$ENABLE_BEHAVIOR_CHANGE_BUNDLE('2021_02') |
|-------------------------------------------------|
| ENABLED                                         |
+-------------------------------------------------+

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Disabling a Behavior Change Bundle in Your Account¶

To disable a particular behavior change in your account, use the SYSTEM$DISABLE_BEHAVIOR_CHANGE_BUNDLE function and specify the bundle_name that contains the change:

SELECT SYSTEM$DISABLE_BEHAVIOR_CHANGE_BUNDLE('2021_02');

+-------------------------------------------------+
| SYSTEM$DISABLE_BEHAVIOR_CHANGE_BUNDLE('2021_02')|
|-------------------------------------------------|
| DISABLED                                        |
+-------------------------------------------------+

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Mitigating Masking Policy Return Value Updates¶

This section describes updates to NULL return values and return values for length, precision and scale in masking policy conditions (collectively: 《return value updates》), and how to use the BCR_2022_07_DDM_ROLLOUT temporary view (in the SNOWFLAKE.BCR_ROLLOUT schema) to mitigate these return value updates.

During the testing period of the 2022_08 behavior change bundle, Snowflake fails queries when the following are true:

• The behavior change bundle is enabled, and

• Querying a column with masking policy when:

  • The masking policy conditions return NULL for a column field that is NOT NULL.

    For example, the masking policy returns NULL for a field that should be an integer because the column data type is INTEGER.

  • The masking policy conditions return a value whose length, scale, or precision is greater than the length, scale, or precision of the column to which the masking policy is assigned. For example:

    Create a policy:

    create masking policy mp as (s string)
    returns string -> 'abcdef';
    

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    Assign the policy:

    create table t(col1 string(2));
    
    alter table t modify column col1 set masking policy mp;
    

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    Query the column (fails):

    select * from t;
    

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To determine the impact of this change and provide enough time to update the masking policy conditions to protect data, Snowflake provides a special schema and view within the shared SNOWFLAKE database to map the table column, masking policy, and a possible reason for why a query on a masking policy-protected column fails.

Note that the return value updates will be enabled by default when the 2023_01 behavior change bundle (i.e. the opt-out period for the 2022_08 behavior change bundle) is published. During the opt-out period, the option to disable the behavior change bundle is available to further delay the effects of the return value updates.

The BCR_2022_07_DDM_ROLLOUT view is temporary. Snowflake will remove the view when the return value updates are generally enabled when the 2023_02 behavior change bundle is published. At this point, it will no longer be possible to query the view to determine affected columns and policies, or prevent column query or masking policy assignment operation failures due to return value updates.

For details on the behavior change process, see Behavior Change Policy.