# Set up matching rules for rule-based Identity Resolution in Connect Customer ## Limits You can select any attribute from the standard profile to compare similar profiles. For example, you might choose phone number, email address, and name, as well as custom attributes. You can create a rule-based matching rule with the following limitations: + 15 rule levels + Each rule level can contain up to 15 profile attributes ## Tips To improve the targeting of unique profiles and to avoid consolidating profiles that are not duplicates, the following tips are recommended: + Include at least one high cardinality attribute that can uniquely identify a customer and that is not likely to be the same across customers, such as a phone number, an email address or an account number. + Avoid using profile attributes that can belong to different identities without a high cardinality attribute. + **Phone number** with **First name**, **Last name** is a stronger rule than the combination of **First name**, **Last name** alone. + If at one rule level, all of the profile attributes of that rule are low cardinality attributes (the attribute that can belong to more than 500 different profiles), Customer Profiles does not attempt to match the profile. You will receive the following SQS message in your DLQ if you setup one during the domain creation: + All attributes at rule level x are associated with more than 500 records. + Always enable **Match only** first, check the match results, and only enable the merging by setting the **MaxAllowedRuleLevelForMerging** if you are satisfied with the match results. ## Resolve profile conflicts for profile merging You can define which record to use when the value of an attribute from two or more similar profiles is different, such as conflicting address records. **Last updated timestamp** By default, profile conflicts are managed by recency. When there is a conflict between the values of two or more similar profiles, the most recently updated attribute will be chosen. **Source with last updated timestamp** Allows you to prioritize records from a specific object type as your data source for managing profile conflicts. When there is a conflict between the values of two or more similar profiles, the most recently updated attribute from the specified object type will be chosen. If a timestamp is not specified in your object type, the date the record was ingested into Customer Profiles will be used. Source with last updated timestamp is unavailable when you don't have any integrations set up. When you add an integration, your object types will be available as a source for this option. ## Missing timestamp for profile conflicts The Missing timestamp message is displayed if you have custom object type mappings. Use the [PutProfileObjectType](https://docs.aws.amazon.com/customerprofiles/latest/APIReference/API_PutProfileObjectType.html) API to add the following new attributes to your custom object type: + `Fields.sourceLastUpdatedTimestamp` + `sourceLastUpdatedTimestampFormat` If the timestamp attribute is not specified, you can continue to create consolidation criteria, however, a default timestamp of when the records were ingested into Customer Profiles is used. It is recommended to add the new attributes before creating your consolidation criteria. If you have already defined a custom object type and want to update your custom object type, we run a scheduled backfill every week to update your existing profiles with the `Fields.sourceLastUpdatedTimestamp`. To opt in to the scheduled backfill, use the following steps: 1. Update your custom profile object type by using the [PutProfileObjectType](https://docs.aws.amazon.com/customerprofiles/latest/APIReference/API_PutProfileObjectType.html) API. 1. After you update your custom profile object type, open an [AWS Support ticket](https://console.aws.amazon.com/support/home). 1. AWS will schedule the backfill on your behalf. The scheduled backfill runs until end of February 2022. Alternatively, you can delete and then re-create the ingestion/connector you have for your domain that uses the custom object type. All of your data will be re-ingested using your updated object type and `Fields.sourceLastUpdatedTimestamp` will be parsed from it. ## Example: How matching works ### Example for ONE\_TO\_ONE You can choose `ONE_TO_ONE` as the `AttributeMatchingModel`. When choosing `ONE_TO_ONE` the system can only match if the sub-types are exact matches. **For example**: You are using the `EmailAddress` and `BusinessEmailAddress` to represent the `EmailAddress` types. The `AttributeMatchingModel` is `ONE_TO_ONE`. **Your matching rule is**: ``` Rule Level 1: EmailAddress, LastName, FirstName Rule Level 2: AccountNumber ``` ``` Profile A: EmailAddress: 1@email.com BusinessEmailAddress: john@company.com LastName: Doe FirstName: John AccountNumber: account1234 ``` ``` Profile B: EmailAddress: 2@email.com BusinessEmailAddress: john@company.com LastName: Doe FirstName: John AccountNumber: account1234 ``` The Profile A and Profile B matches at rule level 1 since the `EmailAddress` type, `LastName`, and `FirstName` match. ### Example for MANY\_TO\_MANY You can choose `MANY_TO_MANY` as the `AttributeMatchingModel`. When choosing `MANY_TO_MANY`, the system can match attributes across the sub-types of an attribute type. **For example**: You are using the `EmailAddress` and `BusinessEmailAddress` to represent the `EmailAddress` types. The `AttributeMatchingModel` is `MANY_TO_MANY`. **Your matching rule is**: ``` Rule Level 1: EmailAddress, LastName, FirstName Rule Level 2: AccountNumber ``` ``` Profile A: EmailAddress: 1@email.com (match with Profile B’s BusinessEmailAddress) BusinessEmailAddress: john@company.com LastName: Doe FirstName: John AccountNumber: account1234 ``` ``` Profile B: EmailAddress: 2@email.com BusinessEmailAddress: 1@email.com (match with Profile A's EmailAddress) LastName: Doe FirstName: John AccountNumber: account1234 ``` The Profile A and Profile B matches at rule level 1 since the `EmailAddress` type, `LastName`, and `FirstName` match.