Django: prefetch related: for loop: based on how we call for loop, the number of sql call varies

Question

In django i am trying to understand prefetch:

I have two for loop scenarios after prefetch

symbollist = SymbolList.objects.prefetch_related('some_related_name')[0:10]
for i in range(0,10):
    print(symbollist[i].some_related_name)

Now it calls sql N+1 times

where as

symbollist = SymbolList.objects.prefetch_related('some_related_name')[0:10]
for symbol in symbollist:
    print(symbol.some_related_name)

this will call only two sqls

Why so

Answer 1

You are limiting symbol_list Queryset to 10 objects and caching related data for them using prefetch_related

but you are iterating through all the objects in database (notice count)

for i in range(0,symbollist.count()):