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Create Detection Rule

For an example of how to create a detection rule for a specific use case, see getting-started:get-started-with-data-quality.adoc.

Before you start

We recommend checking the following topics:

Create new detection rule

As well as being created from scratch, detection rules can be created from the attribute statistics. For example, create a detection rule for a term identifying North American phone numbers using mask results from an existing data profile.

Use mask results in rule

To create a rule:

  1. Navigate to Data Quality > Rules.

  2. Click Create.

    Rules listing
  3. Provide the following information:

    • Name: The name of the rule.

    • Description (optional): A description of the rule and how to use it.

    • Rule definition source (optional): A descriptive name for the data source associated with the rule.

    • Owner (recommended): Select the owner of the rule. Owners are responsible for the accuracy of the information provided and need to approve any changes made to the rule before the rule is published.

    • Steward: Select the data steward of the rule. Data stewards are typically subject matter experts in a specific domain and their role is to define data quality rules and the related glossary terms.

  4. Click Save to create a draft of the rule.

    Missing rule implementation
  5. Before publishing or submitting an approval request, you need to define the rule logic consisting of at least one input attribute and condition. Continue to Rule implementation.

Rule implementation

Once you have created the rule, go to the Implementation tab.

Inputs

  1. Add input attributes and select the data types.

    Input attributes are abstract at this point. The number of input attributes defined here and their rule logic become available when you assign rules to catalog items.

    The attribute names can be as you choose and do not affect the implementation.

    Inputs
    1. (Optional) Assign terms to the attribute.

      Assigning terms to input attributes during implementation results in this rule being suggested by the system in the instance an attribute also has this term.
    2. (Optional) Create Variables from your inputs. Within the Variables section, you can apply a range of transformations to your input attribute. For example, apply the rule conditions only on trimmed versions of string attributes. To create variables:

      • Select a name for your variable. To add fields for additional variables, select Add Variable.

        As with the input attribute names, choose a meaningful name or leave as default.
      • Select the attributes on which the transformations are applied. Use the dropdown to select from the list of input attributes - you apply the transformations in the next step.

        Alternatively, if you are an advanced user, use the dropdown to select Advanced Expression and define the attribute and the transformations using ONE expression language.

      • Add transformations using the Add transformation option. The transformations available depend on the data type of the selected attribute: a full list of types and available transformations is provided below.

        You can apply multiple transformations to one attribute, but you can only add them in a sensical sequence. For example, if you start with an attribute of data type String and apply the transformation To integer, you will not then be able to add the Uppercase transformation, as this is only available on string.

        For the same reason, you can only remove the last transformation in a sequence at any given time. To remove the transformation, hover over the last transformation and use the x to delete.

        Expand to see all available transformations
        Datatype Available transformations Description

        String

        To float

        Changes data type from string to float.

        To integer

        Changes data type from string to integer.

        To long

        Changes data type from string to long.

        Uppercase

        Converts string characters to uppercase.

        Lowercase

        Converts string characters to lowercase.

        Trim

        Removes spaces from both ends of the string.

        Squeeze spaces

        Trims string and replaces repeated spaces with a single space.

        Remove non-digits

        Removes non-digit characters from string.

        Remove non-letters

        Removes non-letter characters from string.

        Integer

        To float

        Changes data type from integer to float.

        To date

        Changes data type from integer to date.

        To long

        Changes data type from integer to long.

        Boolean

        To String

        Changes data type from Boolean to string.

        Date

        To datetime

        Changes data type from date to datetime.

        To string

        Changes data type from date to string.

        Datetime

        To date

        Changes data type from datetime to date.

        To string

        Changes data type from datetime to string.

        Long

        To float

        Changes data type from long to float.

        To string

        Changes data type from long to string.

        To date

        Changes data type from long to date.

        To datetime

        Changes data type from long to datetime.

        Float

        To string

        Changes data type from float to string.

        Floor

        Rounds to the nearest integer that is less than or equal to float value.

        Ceiling

        Rounds to the nearest integer that is greater than or equal to float value.

        Round

        Rounds to nearest integer.

Rule logic

First, in Rule Logic use the dropdown to select Detection

Now provide the rule conditions and an explanation of the result. There are two ways to do this: through the Condition Builder or via Advanced Expression:

+ image::create-detection-rule-condition-builder.png[Condition builder or advanced expression,500]

  • Select Advanced Expression to leverage ONE expressions in your rule condition (see ONE Expressions).

  • Select Condition Builder to define the rule logic using the predefined options.

    Keep in mind that if you’re using the Condition Builder to define the rule logic, a record must pass all the conditions for the rule to result in a term being assigned (the default logical operator between conditions is AND).

    If your detection rule should be less strict and use the logical operator OR, try the Advanced Expression mode.

If you selected Advanced Expression, provide the expression in the space provided and proceed to Test rule.

If you selected Condition Builder:

  1. Select the input attribute or variable to use in the condition.

  2. Select any required modifiers, for example, Trim or Round. Different modifiers are available for string and integer inputs.

    Only string modifiers are available in metadata-based rule conditions.
    Expand to see all available modifiers
    Modifier Description

    Value

    The given value of an attribute.

    Uppercase

    Uppercase version of string.

    Lowercase

    Lowercase version of string.

    Trim

    Removes any whitespaces from both sides of strings.

    Trim left

    Removes any leading whitespaces from strings.

    Trim right

    Removes any trailing whitespaces from strings.

    Squared

    Squares the value of an integer, float, or long data type attributes.

    Round

    Rounds the value of an integer, float, or long data type attributes to the nearest whole number.

    Average

    Averages the value of integer, float, or long data type attributes (available only when using aggregation rules and grouping).

    Min

    The minimum of string, integer, or long data types attributes (available only when using aggregation rules and grouping).

    Max

    The maximum of string, integer, or long data type attributes (available only when using aggregation rules and grouping).

    Sum

    The sum of of string, integer, or long data type attributes (available only when using aggregation rules and grouping).

    1. Select the condition, for example, matches_mask or contains, and provide the necessary requirements. The options available depend on the data type of the input attributes.

      Expand to see all available conditions
      Condition Description

      Is empty

      When the input is not filled.

      This checks if the field is filled, but a field will not be identified as empty if it is filled with: NULL, Null, null, ., ,, -, _, N/A, n/a, and so on.

      Is not empty

      When the input is filled.

      Is the same as

      When the input is the same as the value you define.

      Is the same as attribute

      When the attribute is the same as the attribute you select.

      Is not the same as

      When the input is not the same as the value you define.

      Is not the same as attribute

      When the attribute is not the same as the attribute you select.

      Is from the following list

      When the attribute belongs to the list you define.

      Is not from the following list

      When the attribute does not belong to the list you define.

      Has length of

      Is the same as the length you define.

      Contains

      When the input contains a substring you define.

      Is from catalog item

      When input belongs to a lookup item built from specified catalog item and attribute.

      During the rule logic definition, if you choose the option is from catalog item, a lookup item will be built automatically from the chosen catalog item and used in the rule.

      Is not from catalog item

      When input doesn’t belong to a lookup item built from specified catalog item attribute or reference data in ONE Data.

      Is from reference data

      When attribute input belongs to the lookup file you select.

      Is not from reference data

      When attribute input does not belong to the lookup file you select.

      Matches mask

      When input corresponds to the mask you define.

      Does not match mask

      When input does not correspond to the mask you define.

      Matches regexp

      When input corresponds to the regular expression you define.

      Does not match regexp

      When input does not correspond to the regular expression you define.

      Is true

      When Boolean input is true.

      Is false

      When Boolean input is false.

      Is unique

      When aggregated group is unique.

      Is not unique

      When aggregated group is not unique.

Test rule

You can optionally test the rule by clicking Test Rule and trying different inputs in the Test section. The results for each input are shown automatically in Message next to the test input row.

Test rule

Publish rule

After the changes are implemented, they need to be published.

Next steps

Attributes matching the defined condition are assigned to the term associated with this rule.

Apply your newly-created detection rule to a term. See Add Rules to Terms.

Once the rule is assigned to a term, you can see this term in the Summary and the Detect term sections of the rule implementation screen.

Detection rule summary

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