panguixin

> Once the KNNVectorField move to core the codec will also move there and if Core is giving the codec then I am little bit concerned if this approach will...

> As long as we have a custom codec, we need to persist delegate information in order to properly create delegate on case of loading from SPI. I dont think...

For existing indices, maybe we can get around this issue by explicitly disabling skipping for the `wildcard` field.

@andrross I was thinking of paging the [`indices` section](https://opensearch.org/docs/latest/api-reference/snapshots/get-snapshot-status/#example-response) returned by the status API, and still returning the response in JSON format. The list API needs to return the response...

@navneet1v Yes, I'm also concerned about compatibility issues if the restrictions on custom codecs are completely liberalized. But in most cases where KNN is used, we only care about the...

> > Note: since we can't get a delegate for SegmentInfoFormat, we must use the default delegate codec's SegmentInfoFormat. > > Was thinking more about this - how would we...

@jmazanec15 I just realized that the KNN codec relies on the custom `DocValuesFormat` and `CompoundFormat`, and there is also no per field `CompoundFormat`.

> One question though, why not follow approach like https://github.com/opensearch-project/custom-codecs/blob/main/src/main/java/org/opensearch/index/codec/customcodecs/Lucene912CustomStoredFieldsFormat.java#L95 and write the delegate to segmentInfo attribute during writer creation for StoredFieldsFormat instead of extending SegmentInfoFormat? At the beginning, I...

> [@bugmakerrrrrr](https://github.com/bugmakerrrrrr) Had a follow up question on this. For codec zstd, it is in the custom-codecs repo. The custom codecs repo exposes the custom codecs via a codec service...