- STRING: ""
- BYTES: b''
- INTEGER: 0
- FLOAT: 0.0
- NUMERIC: 0
- BOOLEAN: FALSE
- TIMESTAMP: 1970-01-01 00:00:00 UTC
- DATE: 1970-01-01
- TIME: 00:00:00
- DATETIME: 1970-01-01T00:00:00
- GEOGRAPHY: POINT(0 0)
- BIGNUMERIC: 0
- ARRAY: []
- STRUCT: NOT_APPLICABLE
- JSON: NULL
LAST_FOUR_CHARACTERS (9):
Masking expression shows the last four characters of text.
The masking behavior is as follows:
- If text length > 4 characters: Replace text with XXXXX,
append last four characters of original text.
- If text length <= 4 characters: Apply SHA-256 hash.
FIRST_FOUR_CHARACTERS (10):
Masking expression shows the first four characters of text.
The masking behavior is as follows:
- If text length > 4 characters: Replace text with XXXXX,
prepend first four characters of original text.
- If text length <= 4 characters: Apply SHA-256 hash.
EMAIL_MASK (12):
Masking expression for email addresses. The masking behavior
is as follows:
- Syntax-valid email address: Replace username with XXXXX.
For example, cloudysanfrancisco@gmail.com becomes
XXXXX@gmail.com.
- Syntax-invalid email address: Apply SHA-256 hash.
For more information, see `Email
mask <https://cloud.google.com/bigquery/docs/column-data-masking-intro#masking_options>`__.
DATE_YEAR_MASK (13):
Masking expression to only show the year of `Date`,
`DateTime` and `TimeStamp`. For example, with the year
2076:
- DATE : 2076-01-01
- DATETIME : 2076-01-01T00:00:00
- TIMESTAMP : 2076-01-01 00:00:00 UTC
Truncation occurs according to the UTC time zone. To change
this, adjust the default time zone using the `time_zone`
system variable. For more information, see the System
variables reference.
Enums
Name
Description
PREDEFINED_EXPRESSION_UNSPECIFIED
Default, unspecified predefined expression. No masking will take place since no expression is specified.
SHA256
Masking expression to replace data with SHA-256 hash.
ALWAYS_NULL
Masking expression to replace data with NULLs.
DEFAULT_MASKING_VALUE
Masking expression to replace data with their default masking values. The default masking values for each type listed as below:
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-28 UTC."],[],[],null,["# Class PredefinedExpression (0.6.16)\n\nVersion latestkeyboard_arrow_down\n\n- [0.6.16 (latest)](/python/docs/reference/bigquerydatapolicy/latest/google.cloud.bigquery_datapolicies_v1.types.DataMaskingPolicy.PredefinedExpression)\n- [0.6.15](/python/docs/reference/bigquerydatapolicy/0.6.15/google.cloud.bigquery_datapolicies_v1.types.DataMaskingPolicy.PredefinedExpression)\n- [0.5.3](/python/docs/reference/bigquerydatapolicy/0.5.3/google.cloud.bigquery_datapolicies_v1.types.DataMaskingPolicy.PredefinedExpression)\n- [0.4.0](/python/docs/reference/bigquerydatapolicy/0.4.0/google.cloud.bigquery_datapolicies_v1.types.DataMaskingPolicy.PredefinedExpression)\n- [0.3.2](/python/docs/reference/bigquerydatapolicy/0.3.2/google.cloud.bigquery_datapolicies_v1.types.DataMaskingPolicy.PredefinedExpression)\n- [0.2.0](/python/docs/reference/bigquerydatapolicy/0.2.0/google.cloud.bigquery_datapolicies_v1.types.DataMaskingPolicy.PredefinedExpression)\n- [0.1.1](/python/docs/reference/bigquerydatapolicy/0.1.1/google.cloud.bigquery_datapolicies_v1.types.DataMaskingPolicy.PredefinedExpression) \n\n PredefinedExpression(value)\n\nThe available masking rules. Learn more here:\n\u003chttps://cloud.google.com/bigquery/docs/column-data-masking-intro#masking_options\u003e. \n\n - STRING: \"\"\n - BYTES: b''\n - INTEGER: 0\n - FLOAT: 0.0\n - NUMERIC: 0\n - BOOLEAN: FALSE\n - TIMESTAMP: 1970-01-01 00:00:00 UTC\n - DATE: 1970-01-01\n - TIME: 00:00:00\n - DATETIME: 1970-01-01T00:00:00\n - GEOGRAPHY: POINT(0 0)\n - BIGNUMERIC: 0\n - ARRAY: []\n - STRUCT: NOT_APPLICABLE\n - JSON: NULL\n LAST_FOUR_CHARACTERS (9):\n Masking expression shows the last four characters of text.\n The masking behavior is as follows:\n\n - If text length \u003e 4 characters: Replace text with XXXXX,\n append last four characters of original text.\n - If text length \u003c= 4 characters: Apply SHA-256 hash.\n FIRST_FOUR_CHARACTERS (10):\n Masking expression shows the first four characters of text.\n The masking behavior is as follows:\n\n - If text length \u003e 4 characters: Replace text with XXXXX,\n prepend first four characters of original text.\n - If text length \u003c= 4 characters: Apply SHA-256 hash.\n EMAIL_MASK (12):\n Masking expression for email addresses. The masking behavior\n is as follows:\n\n - Syntax-valid email address: Replace username with XXXXX.\n For example, cloudysanfrancisco@gmail.com becomes\n XXXXX@gmail.com.\n - Syntax-invalid email address: Apply SHA-256 hash.\n\n For more information, see `Email\n mask \u003chttps://cloud.google.com/bigquery/docs/column-data-masking-intro#masking_options\u003e`__.\n DATE_YEAR_MASK (13):\n Masking expression to only show the year of `Date`,\n `DateTime` and `TimeStamp`. For example, with the year\n 2076:\n\n - DATE : 2076-01-01\n - DATETIME : 2076-01-01T00:00:00\n - TIMESTAMP : 2076-01-01 00:00:00 UTC\n\n Truncation occurs according to the UTC time zone. To change\n this, adjust the default time zone using the `time_zone`\n system variable. For more information, see the System\n variables reference."]]