How does Salesforce share the work from different users between trigger instance?

Question

Imagine I have 5 users working in a training on the same Sobject type (Parent__c). They all have a page where they can create 50 child objects (Child__c) with the single click of a button.

Assume there exits a Trigger for Child__c. We all now Triggers work bulkified for up to 200 records.

How does Salesforce share the work between trigger instance

• 5 trigger instance for 50 records each are fired
• 3 trigger instance for 200, 200, 50 records are fired

This is relevant to me because my trigger fires a Batch job to prevent Limit execptions from subsequent triggers. If each user gets his own instance (Case 1) I might run into the 5 Batches in Parallel Limit. But even in Case 2 if more than 1000 records are saved in parallel I will hit my limit.

Answer 1

I am positive (based on my research and the feedback in the comments below) that these each are session based. As in, if 5 users save 50 records each, 5 triggers of 50 records each are run. My reasoning behind this thinking is:

• Triggers fire in bulk and have their own Order of Execution
• This Order of Execution includes multiple validation steps.
• If Salesforce bulked up these records it would cause massive problems with validation. Let me show you a scenario:
  • You have 5 users. User A, B, C, D, and E.
  • Users A, B, and C all have valid data.
  • Users D and E have invalid data.
  • In a bulk processing scenario, all 5 would get errors returned for invalid data because of the transaction management of Triggers.
  • In a non-bulk processing scenario, User A, B, and C would process successfully. Users D and E would each receive separate errors on what is wrong in their record set.

I did a bit of research and I could not find any specific Salesforce documentation explaining this, but like I said, I am positive this is how it works (and in my opinion it makes sense to work like this because of transactions).