Function encode_struct 

fn encode_struct(
    _query_ctx: &QueryContextRef,
    struct_value: StructValue,
    builder: &mut DataRowEncoder,
) -> PgWireResult<()>

this function will encode greptime’s StructValue into PostgreSQL jsonb type

Note that greptimedb has different types of StructValue for storing json data, based on policy defined in JsonStructureSettings. But here the StructValue should be fully structured.

there are alternatives like records, arrays, etc. but there are also limitations: records: there is no support for include keys arrays: element in array must be the same type