ALTR Native Classification
ALTR Native Classification uses regular expression-based (regex) classifiers to identify sensitive data in your Snowflake database. Define classifiers using regex patterns and organize them into collections. When you run a classification scan, attach a collection to a data source, and ALTR uses the regex in the classifiers in that collection to look for matches within the randomly sampled data taken from the tables within the data source.
For example, you might create a classifier for Social Security numbers, add it to a collection called PII and run a scan using that collection to determine whether columns contain SSN data.
Each classifier tests the sampled data for matches, and if the results meet the match threshold you’ve defined, the column is included in the classification report. A random sample is taken from individual columns only, never from full rows. This ensures the data is scrambled, cannot be reconstructed and is meaningless on its own.
Configure and run classification scans, and review results directly in ALTR, while the data itself remains in your Snowflake environment.
A classifier pattern is a valid RE2 regular expression (regex) that follows a specific syntax. Learn more. ALTR Native classification uses the pattern to match results contained anywhere in the column data.
Use the ALTR Managed collection, which is a predefined set of classifiers with patterns already configured, or create custom classifiers with a regex pattern of your choice if these system classifiers don’t fit your exact needs.
Learn more about the list of classifiers that ALTR manages.
With ALTR Native classification, ALTR evaluates a fully random sample of data from each table to determine whether columns match the classifiers in your collection. Sampling is used to efficiently assess data patterns without scanning every row in the table.
Sampling Behavior
Random sampling—Rows are selected at random from the table.
User-configurable sample size—Control how much data is sampled by specifying either:
a fixed number of rows, or
a percentage of the total rows in the table.
Default sample size—By default, ALTR samples 1000 rows. This default provides a reasonable starting point, but the appropriate sample size depends on the size and distribution of data in the table
Choose an Appropriate Sample Size
How the Sample is Used
The sample is evaluated against the classifiers in your collection. If a sufficient portion of the sampled values matches a classifier’s pattern (based on the Minimum Match Threshold you defined), then the column is included in the classification report.
The ALTR Managed collection is a predefined set of classifiers created and maintained by ALTR. Use these classifiers to create custom classifiers with a regex pattern of your choice if these system classifiers don’t fit your exact needs.
The following is the list of classifiers added in the ALTR Managed collection.
January 6, 2026
Classifier Name | Description | Pattern |
|---|---|---|
ALTR Managed - Address | Detects physical full addresses | \b([Gg][Ii][Rr] 0[Aa]{2})|((([A-PR-UWYa-pr-uwy][0-9]{1,2})|(([A-PR-UWYa-pr-uwy][A-Ha-hJ-Yj-y][0-9]{1,2})|(([A-PR-UWYa-pr-uwy][0-9][A-Za-z])|([A-PR-UWYa-pr-uwy][A-Ha-hJ-Yj-y][0-9]?[A-Za-z])))) [0-9][A-Za-z]{2})\b |
ALTR Managed - US ZIP Code | Detects US ZIP codes (5-digit and ZIP+4) | \b[0-9]{5}(-[0-9]{4})?\b |
ALTR Managed - UK Postal Codes - Comprehensive | Detects UK postal codes (includes exceptions) | \b([Gg][Ii][Rr] 0[Aa]{2})|((([A-PR-UWYa-pr-uwy][0-9]{1,2})|(([A-PR-UWYa-pr-uwy][A-Ha-hJ-Yj-y][0-9]{1,2})|(([A-PR-UWYa-pr-uwy][0-9][A-Za-z])|([A-PR-UWYa-pr-uwy][A-Ha-hJ-Yj-y][0-9]?[A-Za-z])))) [0-9][A-Za-z]{2})\b |
ALTR Managed - Date | Detects dates | \b(0?[1-9]|1[0-2])[/-](0?[1-9]|[12]\d|3[01])[/-](19|20)\d{2}\b |
ALTR Managed - ITIN | Detects Individual Taxpayer Identification Numbers (ITIN) | \b9\d{2}-[7-8]\d-\d{4}\b |
ALTR Managed - Email Address | Detects email addresses | \b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}\b |
ALTR Managed - US Phone Number | Detects US phone numbers in various formats | \b(\+1[-.\s]?)?(\(?\d{3}\)?[-.\s]?)\d{3}[-.\s]?\d{4}\b |
ALTR Managed - UK Phone Number | Detects UK phone numbers | \+44(?:\s?\d){10}|0(?:\s?\d){10} |
ALTR Managed - US Social Security Number | Detects US Social Security Numbers (SSN) | \b[0-8]\d{2}[-\s]\d{2}[-\s]\d{4}\b |
ALTR Managed - HIPAA PHI National Drug Code | Detects HIPAA PHI National Drug Codes | \b\d{4,5}-\d{3,4}-\d{1,2}\b |
ALTR Managed - URLs | Detects URLs (to social media etc.) | \b(https?:\/\/)?(www\.)?[-a-zA-Z0-9@:%.\+~#=]{1,256}\.[A-Za-z]{2,24}\b([-a-zA-Z0-9()@:%\+.~#?&\/=]*) |
ALTR Managed - Vehicle Registration UK | Detects UK vehicle registration numbers | \b[A-Z]{2}\d{2}\s?[A-Z]{3}\b |
ALTR Managed - IBAN | Detects International Bank Account Numbers | \b[A-Z]{2}\d{2}[A-Z0-9]{11,30}\b |
ALTR Managed - Credit Cards | Detects credit card numbers | (?:4\d{3}|5[1-5]\d{2}|6011)(?:\s\d{4}\s\d{4}\s\d{4}|-\d{4}-\d{4}-\d{4}|\d{12})|3[47]\d{2}(?:\s\d{6}\s\d{5}|-\d{6}-\d{5}|\d{11}) |
ALTR Managed - SWIFT BIC Code | Detects SWIFT/BIC bank codes | \b[A-Z]{4}[A-Z]{2}[A-Z0-9]{2}([A-Z0-9]{3})?\b |
ALTR Managed - Latitude | Detects latitude coordinates | ^([^,]*[\s:])?[+-]?(90(\.0+)?|[0-8]?\d(\.\d+)?)(\s[^,]*)?$ |
ALTR Managed - Longitude | Detects longitude coordinates | ^([^,]*[\s:])?[+-]?(180(\.0+)?|(1[0-7]\d|[0-9]?\d)(\.\d+)?)(\s[^,]*)?$ |
ALTR Managed - IPv4 Address | Detects IP addresses | ((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?) |
ALTR Managed - IPv6 Address | Detects IPv6 addresses | (?:[0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}|(?:[0-9a-fA-F]{1,4}:){1,7}:|(?:[0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|(?:[0-9a-fA-F]{1,4}:){1,5}(?::[0-9a-fA-F]{1,4}){1,2}|(?:[0-9a-fA-F]{1,4}:){1,4}(?::[0-9a-fA-F]{1,4}){1,3}|(?:[0-9a-fA-F]{1,4}:){1,3}(?::[0-9a-fA-F]{1,4}){1,4}|(?:[0-9a-fA-F]{1,4}:){1,2}(?::[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:(?::[0-9a-fA-F]{1,4}){1,6}|:(?::[0-9a-fA-F]{1,4}){1,7}|:: |
ALTR Managed - MAC Address | Detects MAC addresses | (?:[0-9A-Fa-f]{2}[:-]){5}[0-9A-Fa-f]{2}|(?:[0-9A-Fa-f]{4}\.){2}[0-9A-Fa-f]{4} |
ALTR Managed - ABA Routing Number | Detects US ABA bank routing numbers | \b(?:0[0-9]|1[0-2]|2[1-9]|3[0-2]|6[1-9]|7[0-2]|8[0-0])[0-9]{7}\b |
ALTR Managed - UUID GUID | Detects UUIDs/GUIDs | \b[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}\b |
ALTR Managed - AWS Access Key ID | Detects AWS Access Key IDs | \b(?:AKIA|ABIA|ACCA|ASIA)[0-9A-Z]{16}\b |
ALTR Managed - Private Key Header | Detects private key file headers | -----BEGIN\s(?:RSA\s|EC\s|DSA\s|OPENSSH\s)?PRIVATE\sKEY----- |
ALTR Managed - JWT Token | Detects JSON Web Tokens | eyJ[A-Za-z0-9_-]*\.eyJ[A-Za-z0-9_-]*\.[A-Za-z0-9_-]* |
ALTR Managed - Medicare Beneficiary ID | Detects Medicare Beneficiary Identifiers (MBI) | \b[1-9][AC-HJKMNP-RT-Y][AC-HJKMNP-RT-Y0-9][0-9][AC-HJKMNP-RT-Y][AC-HJKMNP-RT-Y0-9][0-9][AC-HJKMNP-RT-Y]{2}[0-9]{2}\b |
ALTR Managed - NPI Number | Detects National Provider Identifier numbers | \b[12][0-9]{9}\b |
ALTR Managed - EU VAT Number | Detects European Union VAT numbers | \b(?:AT)?U[0-9]{8}\b|\b(?:BE)?[01][0-9]{9}\b|\b(?:BG)?[0-9]{9,10}\b|\b(?:CY)?[0-9]{8}[A-Z]\b|\b(?:CZ)?[0-9]{8,10}\b|\b(?:DE)?[0-9]{9}\b|\b(?:DK)?[0-9]{8}\b|\b(?:EE)?[0-9]{9}\b|\b(?:EL|GR)?[0-9]{9}\b|\b(?:ES)?[A-Z0-9][0-9]{7}[A-Z0-9]\b|\b(?:FI)?[0-9]{8}\b|\b(?:FR)?[A-Z0-9]{2}[0-9]{9}\b|\b(?:HR)?[0-9]{11}\b|\b(?:HU)?[0-9]{8}\b|\b(?:IE)?[0-9][A-Z0-9+*][0-9]{5}[A-Z]{1,2}\b|\b(?:IT)?[0-9]{11}\b|\b(?:LT)?(?:[0-9]{9}|[0-9]{12})\b|\b(?:LU)?[0-9]{8}\b|\b(?:LV)?[0-9]{11}\b|\b(?:MT)?[0-9]{8}\b|\b(?:NL)?[0-9]{9}B[0-9]{2}\b|\b(?:PL)?[0-9]{10}\b|\b(?:PT)?[0-9]{9}\b|\b(?:RO)?[0-9]{2,10}\b|\b(?:SE)?[0-9]{12}\b|\b(?:SI)?[0-9]{8}\b|\b(?:SK)?[0-9]{10}\b |
A classifier is a rule, defined by a regular expression, used to identify specific types of data within a column. Classifiers are logically grouped together into a collection.
Use ALTR’s system classifiers (contained within the ALTR Managed collection) and/or create custom classifiers. Then, assign those classifiers to a collection. A collection is assigned to a classification scan when data is classified.
ALTR Native classification can use system, ALTR-managed classifiers, or it can use custom classifiers. Create custom classifiers either from the All Classifiers page or from a collection.
To create a classifier:
Select Data Classification in the Navigation menu.
Click Create new to create a custom classifier. It then needs to be added to a collection.
Or
Click a collection name under Collections, then click → to create a custom classifier within a collection. The classifier is also added to the full classifier list so it can be re-used in another collection.
Note
Custom classifiers cannot be added to the ALTR Managed collection.
(Optional) Click +add to collection to add this classifier to a collection.
Enter a Classifier Name that is unique and does not begin with “ALTR.”
Enter a classifier Pattern. This is a valid RE2 regex pattern. Learn more.
(Optional) Enter a brief Description of the classifier, such as what type of data the pattern detects.
Use the classification settings to define how much of the sample must match the classifier pattern and the table sample size in order to classify the column. Learn more about how ALTR takes the data sample. If unsure, use the default settings. If the classification report doesn’t product the results you expected, adjust these classification settings and classify the data again.
Minimum Match Threshold—The minimum percentage of the sampled data that must match the classifier pattern for the column to display in the classification report. The default value is 75%.
Sample by—The sample size measured by either a fraction of the table (table %) or an exact number of rows (row count). The default is to sample by row count with the default value of 1000 rows. When sampling by table %, the default value is 10% of the table.
ALTR's Recommended Sampling
Example
If the Minimum Match Threshold is set to 60% and the Sample by is set to a row count of 500, then 60% of the data in a random sample of 500 rows within the table must match the classifier pattern in order for the column to be classified.
When setting a sample size on a classifier higher than the total amount of rows on the table (so for example a sample size of 1000 on a table with only 100 rows), the classification queries all 100 rows.
Click Save.
Edit a custom classifier (i.e., a classifier you created; not an ALTR Managed classifier) to update the Pattern, Description or the Classification Settings, or to add/remove the classifier to/from a collection. If you need to update the Classifier Name, delete the classifier and create another with the new name.
If your classification report did not show the results you expected (such as, columns you through would be in the report did not display), try lowering the Minimum Match Threshold on the classifier or reduce the sample size.
To edit a classifier:
Locate the classifier either from the View all classifier list or from within a collection.
Click the ellipsis menu for the classifier.
Select Edit classifier; a modal displays.
Update classifier.
Click Save.
Delete a custom classifier (i.e., a classifier you created, not an ALTR Managed classifier) from ALTR if it is no longer needed. It is removed from any collection it is part of and deleted from ALTR. ALTR-managed classifiers cannot be deleted.
Delete a single classifier from ALTR or utilize the bulk delete feature to delete multiple classifiers.
Note
When deleting classifiers, the record is instantly removed from the page, but it may take several minutes for the classifier count to update.
To delete a classifier from ALTR:
Locate the classifier either from the View all classifier list or from within a collection.
Click the ellipsis menu.
Select Delete classifier; a modal displays to confirm.
Click Delete Classifier.
To bulk delete classifiers from ALTR:
Click Data Classification in the Navigation menu.
Select classifiers.
Click Delete; a modal displays.
Note
If an ALTR Managed classifier is selected, the Delete button becomes disabled because you cannot delete ALTR Managed classifiers from ALTR. Deselect the ALTR Managed classifiers to enable deletion.
Click Delete Classifiers.
Remove a classifier from a collection if it’s no longer needed in the collection, but it may still be in another collection or you don’t want to delete it from ALTR.
You can remove a classifier from a collection in either of the following ways:
From the classifier
From the collection
To remove classifier from a collection:
Click the collection under Collections.
Search for the classifier name.
Click the ellipsis menu for the classifier.
Select Remove from collection.
To remove a collection assignment from a classifier:
Click View all classifiers under Overview.
Search for the classifier name.
Click the ellipsis menu for the classifier.
Click Edit classifier.
Under Appears in collection, click the X on the collection to remove it from the list.
Click Save.
A collection is a logical grouping of one or more classifiers that is assigned to a classification scan. The Snowflake data source is evaluated only using the relevant classifiers. Collections let you organize classifiers by data type, compliance requirement or business use case.
For example, you might create collections as:
PII—classifiers for email addresses, Social Security numbers and phone numbers
Financial data—classifiers for credit card numbers and bank account numbers
Compliance-focused—classifiers aligned to requirements like PCI or GDPR
Application-specific—classifiers for internal customer or employee identifiers
ALTR creates and maintains a pre-defined set of classifiers in the ALTR Managed collection. This collection is useful if you don’t know what classifiers you want to use or if you want to test the functionality.
To use these classifiers in your own collection, you must import the ALTR Native collection. This is a one-time process for your organization.
Import ALTR Managed Collection
Once imported,
the classifiers can be added to any collection
the collection can be duplicated and modified to meet your needs
Note
ALTR-managed classifiers cannot be directly edited or deleted from ALTR.
To import the ALTR Managed collection:
Select Data Classification in the Navigation menu.
Click ALTR Managed under Collections.
Click Import ALTR Managed Collection.
Sync ALTR Managed Collection
As ALTR adds classifiers to the ALTR Managed collection, you have the option to view the new classifiers and sync the collection to your organization.
Note
If you have generated a classification report using the ALTR Managed collection and you sync the collection, you must re-classify the data in order to generate a new report if you wish to include the added classifiers.
To sync the ALTR Manage collection with your organization:
Click Data Classification in the Navigation menu.
Click ALTR Managed under Collections.
Click Sync Classifiers; a modal displays. If the button is disabled, the collection is up to date and there are no new classifiers to sync.
(Optional) Click View latest classifiers link to view the classifier change log to see the list of new ALTR Managed classifiers that have been added to the collection since it was last synced with your organization.
Click Sync.
Create a collection, add classifiers and use that collection when you classify data. Manually create a collection or duplicate an existing collection.
Once a collection is created, the name cannot be updated. To change the collection name, duplicate the collection and save it with a new name.
To create a collection:
Click Data Classification in the Navigation menu.
Click Create a new collection +.
Enter a Collection Name that is unique and does not begin with “ALTR.”
(Optional) Enter a Description for the collection that describes the type of data within the collection.
Click Next.
(Optional) Select classifiers to add to your collection.
Click Next.
Review your collection details. You can edit these later if need be.
Click Save.
Duplicating a collection creates a copy of a collection, including all if its classifiers. This lets you quickly reuse and adapt a set of classifiers without starting from scratch. You might duplicate a collection to customize it for a different Snowflake database or schema, test changes without affecting the original collection, or create variations for different teams or use cases.
To duplicate a collection:
Click Data Classification in the Navigation menu.
Select the collection name under Collections.
Click the ellipsis menu for the collection.
Select Duplicate collection; a modal displays.
Enter a Collection Name that is unique and does not begin with “ALTR.”
(Optional) Enter a Description for the collection that describes the type of data within the collection.
Click Next.
Review your collection details. You can edit these later if need be.
Click Save.
Delete a collection from ALTR if you no longer need it. Individual classifiers remain available (i.e., they are not deleted) and can still be used in other collections.
Note
Once the ALTR Managed collection is imported, it cannot be deleted from ALTR.
To delete a collection:
Click Data Classification in the Navigation menu.
Select the collection name under Collections.
Click the ellipsis menu for the collection.
Select Delete collection; a modal displays.
Click Delete Collection.