Merge branch 'master' into evanSegment-hubspot-correction

Author: markzegarelli

src/personas/rate-limits.md

@@ -12,6 +12,8 @@ These rate limits were added to our product documentation on December 9, 2020.
 | Inbound Historical Replay Throughput        | 1000 events per second                                      |
 | Outbound Downstream Destination Rate Limits | Reduced retries when failures exceed 1000 events per second |
 | Profile API throughput                      | 100 requests per second                                     |
+| Identity Merges                             | 100 merges                                                  |
+| Identity Mappings                           | 1000 mappings                                               |
 
 ## Inbound Data Throughput
 
@@ -28,3 +30,11 @@ Most destinations have their own rate limits that Segment cannot control. In som
 ## Profile API throughput
 
 If a Customer sends more than 100 requests a second per space to the Profile API, Segment will return a 429 rate-limiting error. Any requests to raise that limit must be made in writing with Segment. Please reach out to [email protected] with details on your use case and estimated throughput.
+
+## Identity Merges
+
+Personas supports up to 100 merges per profile in its identity graph. A merge occurs when two existing profile are joined together by a common external_id. For example, if a user starts their journey on mobile, and then signs in via a web application, those two user profiles are joined together by a common identifier like a user_id. Messages that attempt additional merges are usually a sign of a corrupt profile and are dropped.
+
+## Identity Mappings
+
+Personas supports up to 1000 mappings per profile in its identity graph. Mappings are external id values like a user_id, email, mobile advertising id, or any custom id's. Messages that attempt to add additional mappings are usually a sign of a corrupt profile and are dropped. Note that this limit counts mappings across all merged profiles.