Basically, in the past, if you had a query like this:
query = MyEntity.all().filter('attribute1 =',
'foo').filter('attribute2 =', 'bar').filter('attribute3 =',
'baz').order('-attribute4)
you'd need an index like this:
- kind: MyEntity
properties:
- name: attribute1
- name: attribute2
- name: attribute3
- name: attribute4
direction: desc
Call this an optimal index.
Now, the query engine is able to make due with non-optimal indexes; in
some cases you may not even need a custom composite index at all.
Fewer composite indexes means fewer datastore write operations (and
thus $$), but you will likely trade off performance (and thus
increased instance-hours, unless you are multi-threaded) as the query
engine needs to walk through more potential matches when using non-
optimal indexes.
A good starting point is to remove all of your indexes from index.yaml
(on dev, of course!) and see what dev_appserver makes for suggestions.
j
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