Merge pull request #3078 from segmentio/audience-timestamp-limits

Personas Event Timestamp Limit

Author: pwseg

src/personas/product-limits.md

@@ -37,12 +37,13 @@ To learn more about custom limits and upgrades, contact your dedicated Customer
 
 ## Audiences and Computed Traits
 
-| name                    | limit                                             | Details                                                                                                                                                                                                |
-| ----------------------- | ------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
-| Compute Concurrency     | 5 concurrent audiences                            | Segment computes five new audiences or computed traits at a time. Once the limit is reached, Segment queues additional audience computations until one of the five audiences finishes computing.       |
-| Compute Throughput      | 10000 computations per second                     | Computations include any Track or Identify call that triggers an audience or computed trait re-computation. Once the limit is reached, Segment may slow audience processing.                           |
-| Events Lookback History | **Essentials**: 1 year <br><br> **Advanced**: 3 years | The period of time for which Segment stores audience and computed traits computation events.  This limit depends on your Personas service. Contact your account team to upgrade your Personas service. |
-| Real-time to batch destination sync frequency | 2-3 hours   | The frequency with which Segment syncs real-time audiences to batch destinations.  |
+| name                                          | limit                                                 | Details                                                                                                                                                                                                |     |
+| --------------------------------------------- | ----------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | --- |
+| Compute Concurrency                           | 5 concurrent audiences                                | Segment computes five new audiences or computed traits at a time. Once the limit is reached, Segment queues additional audience computations until one of the five audiences finishes computing.       |     |
+| Compute Throughput                            | 10000 computations per second                         | Computations include any Track or Identify call that triggers an audience or computed trait re-computation. Once the limit is reached, Segment may slow audience processing.                           |     |
+| Events Lookback History                       | **Essentials**: 1 year <br><br> **Advanced**: 3 years | The period of time for which Segment stores audience and computed traits computation events.  This limit depends on your Personas service. Contact your account team to upgrade your Personas service. |     |
+| Real-time to batch destination sync frequency | 2-3 hours                                             | The frequency with which Segment syncs real-time audiences to batch destinations.                                                                                                                      |     |
+| Event History                                 | `1970-01-01`                                          | Events with a timestamp less than `1970-01-01` aren't always ingested, which could impact audience backfills with event timestamps prior to this date.                                                |
 
 ## SQL Traits
 
@@ -58,7 +59,7 @@ To learn more about custom limits and upgrades, contact your dedicated Customer
 
 | Item         | Limit description                | Details                                                                      |
 | ------------ | -------------------------------- | ---------------------------------------------------------------------------- |
-| Steps        | 500                              | The maximum number of steps per Journey.                                     | 
+| Steps        | 500                              | The maximum number of steps per Journey.                                     |
 | Step Name    | Maximum length of 170 characters | Once the limit is reached, you cannot add additional characters to the name. |
 | Key          | Maximum length of 255 characters | Once the limit is reached, you cannot add additional characters to the key.  |
 | Journey Name | Maximum length of 73 characters  | Once the limit is reached, you cannot add additional characters to the name. |