Question

I have a class like:

class Test {
    String id1;
    String id2;
    List<String> stuff;
}

if I need to run this query:

select from Test where id1='a' && id2='b' && stuff='foo';

am I going to get exploding indices?

Thanks

Answer 1

The most “explosive” type of entity is one that has 2 (or more) different List properties and you have a custom index that uses both lists (thanks to nick for the clarification about using a custom index) That is because the datastore will need to create an index entry for all permutations of items from both lists. For example, if one list contains “a”, “b”, “c” and the second list contains 1 and 2, a bunch of entries would be needed:

a,1
b,1
c,1
a,2
b,2
c,2

In your case, the datastore should only need to create one entry per item in your “stuff” list.
More details here