Add FAQ to Salesforce (Actions) (#3959)

Author: kdaswani

src/connections/destinations/catalog/actions-salesforce/index.md

@@ -103,3 +103,9 @@ To check how many API calls you have left in Salesforce, go to **Setup > Company
 When using the `create` operation, it's possible for duplicate records to be created in Salesforce. This is because Segment retries records once they hit the internal timeout. It's possible Salesforce's REST API eventually processes the original record in addition to the retried record, resulting in duplicates. You may encounter this behavior if Salesforce's REST API throttles your records (for example, due to hitting API limits or complex workflow automation). To prevent duplicates, you can use [Duplicate Rules](https://help.salesforce.com/s/articleView?id=duplicate_rules_map_of_reference.htm&language=en_US){:target="_blank"} in Salesforce. See set up information in [Resolve and Prevent Duplicate Data in Salesforce](https://trailhead.salesforce.com/content/learn/modules/sales_admin_duplicate_management/sales_admin_duplicate_management_unit_2){:target="_blank"}.
 
 Please note this is only a concern when using the `create` operation. You can use the `upsert` operation instead to avoid duplicates if `upsert` meets your needs.
+
+### How does Salesforce Bulk API work?
+When **Use Salesforce Bulk API** is enabled for your mapping, events are sent to [Salesforce’s Bulk API 2.0](https://developer.salesforce.com/docs/atlas.en-us.api_asynch.meta/api_asynch/asynch_api_intro.htm){:target="_blank"} rather than their streaming REST API. If enabled, Segment will collect events into batches of 1000 before sending to Salesforce. Bulk support can be used for the `upsert` or `update` operations only.
+
+For bulk `update`, if a record in a batch is missing a Bulk Update Record ID, Segment will still send it to Salesforce. Salesforce will reject the individual record because it will be unable to find a record to update. Other records in the batch that are valid will still be processed. Please note that Segment's Event Delivery tab will show the entire batch as successful as Segment cannot currently break down Event Delivery stats into individual failed/passed events.
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