Are the index Bigtables in google app engine unique for each application?

Google App Engine's documentation states that:

Four Bigtables are used to store all indexes for every App Engine application

In contrast, the same document states following about entities:

This one Bigtable holds all entities for all App Engine applications.

Noting the use of "every App Engine Application" instead of "all App Engine Application", I understand that while the entities Bigtable is global to all applications, index Bigtables are unique to each application.

Is my understanding correct? Also, does this difference have any开发者_开发百科 significance for an average app engine developer?

I think that (at least in this case) "all" and "every" mean exactly the same thing. There are 5 Bigtables discussed here, four for indexes and one for entities. Those tables cover all apps.

If the first quote had said "for every App Engine application, there are four Bigtables", even better "for each App Engine application, there are four Bigtables", then it would mean what you thought.

Blame English -- operator precedence means that the sentence should be read, "Four Bigtables are used to store (all indexes for every App Engine application)", not "(Four Bigtables are used to store all indexes) for every App Engine application".