GORM Golang：克隆数据库实例的目的

Question

In few pass week I just learn about GORM as the database ORM. After checking inside the code, every command (limit, order, where, or, select, etc) are returning new instance by cloning the current DB.
Is there anyone here know what is the main purpose of cloning the DB instead of using the current instance?
When I have command select, where, limit, order, join, that will be 5 times of cloning the DB instance. AFAIK, creating object on the memory are expensive.

Answer 1

The purpose is to be able to store "temporary" instance of your query to be able to derive them later. That is, if you have a number of queries which share the some part of the sequence, you should be able to do something like

q := gorm.Select(...).Limit(...).Order(...)
q1 := q.Where(...)
q2 := q.Where(...)

(This example is a rought example that probably doesn't even map to GORM API as I don't use it myself.)

Now, I believe that cloning objects in memory that won't be kept long doesn't hinder much performance compared to the cost of doing a SQL query, which imply a network round-trip…