Data types support object type

[liyan186]

What problem does the new feature solve?

Better store the following class

data class OrderBook(
    val symbol: String,
    val timeMillis: Long,
    val asks: List<Book>,
    val bids: List<Book>,
    val status: Boolean
) {
    data class Book(val price: BigDecimal, val size: BigDecimal)
}

What does the feature do?

data types support object type. In this way, asks and bids can store more efficiently.

Implementation challenges

No response

[evenyag]

Thanks for your suggestion! I think we could implement the struct data type, both arrow and parquet support the struct data type.

[tisonkun]

Move to ideas until we have some concrete designs.