Some questions about Indexing for Search

[LemonLiTree]

I use encode data in our system to store S2 data, for example：

        std::string* buf;
        Encoder encoder;
        _polygon->Encode(&encoder);//_polygon is  std::unique_ptr<S2Polygon> _polygon; 
        buf->append(encoder.base(), encoder.length());

In the document introduction, support Indexing for Search
http://s2geometry.io/devguide/cpp/quickstart
Can I build an index on such a data store? If so, is there a sample code that I can refer to, and if that doesn't work, how do I store the data so I can build an index.
Or is there more information about Indexing for Search reference

[smcallis]

You can't index on the encoded data directly, but S2ShapeIndex is designed so that the index and shapes are encoded separately. Here's some examples in EncodedS2ShapeIndex showing how you can add shapes to an index an then encode them and the index separately.

[LemonLiTree]

If my data only involves calculations based on s2index, can I just store EncodedS2ShapeIndex data？ Or store encode shapes and encode index separately？

[smcallis]

You'd encode the shapes and index together in that case most likely, then just read the data into an EncodedS2ShapeIndex with a lazily decode shape factory (usually, you can do a full decode if you want but it's slower since you likely don't need all the shapes).

[LemonLiTree]

Is there any more documentation about Indexing for Search, I want to do a quick query based on a large amount of S2 region data

[smcallis]

I don't think we have anything comprehensive written down. What kind of searches do you want to do?

[LemonLiTree]

just like this

[smcallis]

Ah I'd reference the comments in that file showing how to use it: https://github.com/google/s2geometry/blob/master/src/s2/s2region_term_indexer.h#L1-L95