---
schema_version: "1"
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title: How Match Keys Are Generated and Used in Matching Rules
collection: admin
version: current
locale: en-us
portal_url: https://docs.salesforce.com/admin/current/en-us/sales/264-0-0/matching_rules_match_key_process.md
canonical_url: https://help.salesforce.com/s/articleView?id=sales.matching_rules_match_key_process.htm&release=264.0.0&type=5
source_site: help.salesforce.com
content_type: documentation
content_hash: 6301a01aa6d6e02407e97cf6d5c5bae7dba31f1122f73353b27d6a04808bc138
description: When a matching rule runs, it applies one or more match key formulas before applying a comprehensive matching equation. Match keys help to increase the performance of duplicate rules through a preliminary comparison that narrows the matches to the 100 most likely duplicate records. Then the rule applies the matching equation only to those likely matches.
products:
  - Sales
  - Sales Enablement
release: "264"
---
# How Match Keys Are Generated and Used in Matching Rules

When a matching rule runs, it applies one or more match key formulas before applying a comprehensive matching equation. Match keys help to increase the performance of duplicate rules through a preliminary comparison that narrows the matches to the 100 most likely duplicate records. Then the rule applies the matching equation only to those likely matches.

### Required Editions

<table class="slds-table slds-table_bordered slds-max-medium-table_stacked slds-m-bottom_small edition"><colgroup><col></colgroup><tbody><tr class=""><td class="slds-cell-wrap" style="vertical-align:top;">Available in: Lightning Experience and Salesforce Classic</td></tr><tr class=""><td class="slds-cell-wrap" style="vertical-align:top;">Available in: <strong>Essentials</strong>, <strong>Professional</strong>, <strong>Enterprise</strong>, <strong>Performance</strong>, <strong>Unlimited</strong>, and <strong>Developer</strong> Editions</td></tr></tbody></table>

In rare instances, match keys result in undetected duplicates, but generally, match keys greatly improve the performance of duplicate rules.

## How Match Keys Are Generated

- The matching equation that determines the arrangement of the fields is rewritten into a standardized format that translates the OR statements into AND statements.
- Values for fields in the matching rule are normalized.
- A match key is generated using the field combinations specified in the standardized field format. A matching rule can have multiple match keys. A custom matching rule can have up to 10 match keys; you’re prevented from saving a matching rule that requires more.
- The match key is used to combine normalized field values for each record.

![Note](https://sf-zdocs-cdn-prod.zoominsoftware.com/tdta-sales-data_quality-264-0-0-production-enus/abf88105-66d5-422e-983e-0592556338d7/images/icon_note.png)

Note No match key is generated for the Title field.

The match key notation shows which fields and which characters in those fields are used in a match key.

![Match key diagram](https://sf-zdocs-cdn-prod.zoominsoftware.com/tdta-sales-data_quality-264-0-0-production-enus/abf88105-66d5-422e-983e-0592556338d7/data_quality/images/duplicate_management_match_key_diagram.png)

- The field used in the match key (1).
- Number of words (or tokens) in the field value to include in the match key (2). If no number is present, all words are included.
- Number of characters per word to include in the match key (3). If no number is present, all characters are included.
- Additional field used in the match key (4).

## Match Keys for Standard and Custom Rules

Standard matching rules use predefined match keys. Custom rules that contain standard field combinations also use predefined match keys. For example, the matching rule equation for a custom contact matching rule is (First Name AND Last Name AND Company). A fuzzy matching method is selected for at least one field. The notation for its match key is: First\_Name (1,1) Last\_Name Company (2,6).

For nonstandard field combinations, custom rules use keys generated from their corresponding matching criteria.