AutoId should be more fleixble

[ChristianPardun]

It would be a good idea to make the Auto-ID function more flexible so that it can be defined externally or based on the externally defined primary index fields. This should make the “Upsert” function even more flexible and also the indices of the collection. In the case of a primary index based auto id field, the automatically generated _id index is obsolete in this scenario.

One idea is that it is a number that can then be set to a hash value based on the document index values or some other (and faster way) to be a unique value of the primary key field content.

The Auto-ID function is currently inflexible if you have scenarios with your own primary key indices.