How I can get an specific ID? I have the ID in the metadata of another item.

doc.Query(ctx, "", 1, map[string]string{"id": x.Metadata["reference"]}, nil)

Or I need to add the ID on metadatas?

Currenly I add the data with:
c.Add(ctx, []string{chunk.ID}, embeddings, []map[string]string{addToMapString(map[string]string{"source": fmt.Sprintf("%s:%d", source.Name, i)}, chunk.Metadata)}, []string{chunk.Content})

Thanks