In SQL Server Management Studio, when I "View History" for a SQL Job, I'm only shown the last 50 executions of the Job.
How can I view a full log of every execution of a SQL Job since it was created on the server?
The SQL Server Job system limits the total number of job history entries both per job and over the whole system. This information is stored in the MSDB database.
Obviously you won't be able to go back and see information that has been since discarded, but you can change the SQL Server Agent properties and increase the number of entries that will be recorded from now on.
In the SQL Server Agent Properties:
It won't give you back your history, but it'll help with your future queries!