What is the limit (if there are any) in terms of the number of returned Search results based on certain criteria? It is 2k, 5k or ? We are looking at the S&P 500 and all bonds issued by all entities. This could be around 35k instruments.
You can get all identifiers with one request, such as this:
it yields ~84,156 ISINs (after dropna())
But if you like to get some underlying info on those you will have to package the codes in multiple requests. If I need 3-4 fields, I can easily have 5000 items in my request.