I’m trying to understand more on how entity groups work in GAE. Several places in the documentation, it refers to the fact that “you can only expect to update any single entity or entity group about five times a second.”, and other places it says that multiple users writing to the same entity group at the same time will cause only one of them to succeed (if I understood that correctly). So if I have an entity group Users with 1 million user entities, only 1 user will be able to update his records at any given time, and anyone else who tried will fail? I’m just not understanding entity groups. If I understood correctly, they are sort of like folders? But I don’t get why multiple users can’t make updates to the same entity group at the same time?
Are entity groups just a structural thing? If I have a million users, are they all grouped in an entity group Users (if I specify that)?
In your case Users are a kind.
Entity groups are defined by defining an ancestor relationship between enntities. They are important because they define the scope of transactions.
The limitation of entity groups is that they have a limited write rate.
If ancestor relationship is not defined, then entity is the only entity in the entity group. Write limitation still applies to that entity.
When definig entity groups it’s important to keep them as small as possible and to organize them so to avoid contention (parallel writes) on them. A common way is to make user entity a root of entity group.