Should I denormalize properties to reduce the number of indexes required by App Engine?

One of my queries can take a lot of different filters and sort orders depending on开发者_C百科 user input. This generates a huge index.yaml file of 50+ indexes.

I'm thinking of denormalizing many of my boolean and multi-choice (string) properties into a single string list property. This way, I will reduce the number of query combinations because most queries will simply add a filter to the string list property, and my index count should decrease dramatically.

It will surely increase my storage size, but this isn't really an issue as I won't have that much data.

Does this sound like a good idea or are there any other drawbacks with this approach?

As always, this depends on how you want to query your entities. For most of the sorts of queries you could execute against a list of properties like this, App Engine will already include an automatically built index, which you don't have to specify in app.yaml. Likewise, most queries that you'd want to execute that require a composite index, you couldn't do with a list property, or would require an 'exploding' index on that list property.

If you tell us more about the sort of queries you typically run on this object, we can give you more specific advice.

Denormalizing your data to cut back on the number of indices sounds like it a good tradeoff. Reducing the number of indices you need will have fewer indices to update (though your one index will have more updates); it is unclear how this will affect performance on GAE. Size will of course be larger if you leave the original fields in place (since you're copying data into the string list property), but this might not be too significant unless your entity was quite large already.

This is complicated a little bit since the index on the list will contain one entry for each element in the list on each entity (rather than just one entry per entity). This will certainly impact space, and query performance. Also, be wary of creating an index which contains multiple list properties or you could run into a problem with exploding indices (multiple list properties => one index entry for each combination of values from each list).

Try experimenting and see how it works in practice for you (use AppStats!).

"It will surely increase my storage size, but this isn't really an issue as I won't have that much data."

If this is true then you have no reason to denormalize.