Understanding Soft Delete in Paimon
Paimon is a powerful open-source ORM (Object Relational Mapper) for the Go programming language. It simplifies database interactions by providing a convenient way to map Go structs to database tables. One of the useful features Paimon offers is the concept of soft delete, which allows you to logically delete data from your database without physically removing it.
Why use soft delete?
There are several advantages to using soft delete instead of hard delete:
- Data Recovery: Soft delete allows you to easily recover deleted data if needed. This is particularly important for sensitive information or when dealing with audit logs.
- Historical Data: You can maintain a historical record of deleted data. This is beneficial for analysis, reporting, or even for regulatory compliance purposes.
- Version Control: You can track changes made to data over time. This can be useful for debugging or understanding how the data has evolved.
How does soft delete work in Paimon?
Paimon implements soft delete by adding a deleted_at column to your database table. This column is a timestamp that indicates when a record was logically deleted. When you perform a "delete" operation using Paimon, it doesn't physically remove the row from the table but simply sets the deleted_at timestamp to the current time.
Implementing Soft Delete in Paimon
Here's a basic example of how to implement soft delete using Paimon:
- Define your model:
package main
import (
"time"
"github.com/jinzhu/gorm"
_ "github.com/jinzhu/gorm/dialects/mysql"
)
type User struct {
gorm.Model
Name string
Email string
DeletedAt gorm.DeletedAt `gorm:"index"` // Add DeletedAt field
}
func main() {
db, err := gorm.Open("mysql", "user:password@tcp(127.0.0.1:3306)/test?charset=utf8&parseTime=True&loc=Local")
if err != nil {
panic(err)
}
defer db.Close()
// Create a new user
user := User{Name: "John Doe", Email: "[email protected]"}
db.Create(&user)
// Soft delete the user
db.Delete(&user)
// Query for all users, including soft deleted ones
var users []User
db.Find(&users)
// The `users` slice will include the deleted user, but its `DeletedAt` field will have a timestamp.
// Query for only active users (not soft deleted)
var activeUsers []User
db.Unscoped().Where("deleted_at IS NULL").Find(&activeUsers)
// The `activeUsers` slice will only contain users that haven't been soft deleted.
}
Explanation:
- The
gorm.DeletedAtfield is used to store the timestamp of when a record was deleted. db.Delete(&user)sets thedeleted_atfield for theuserrecord.db.Find(&users)will retrieve all records, including soft deleted ones.db.Unscoped().Where("deleted_at IS NULL").Find(&activeUsers)will retrieve only records that are not soft deleted (those withdeleted_atset to NULL).
Important Considerations:
- Database Design: Make sure your database table has a
deleted_atcolumn of type timestamp or datetime. - Indexing: Index the
deleted_atcolumn for efficient retrieval of soft deleted records. - Querying: When you need to retrieve only active records, remember to add a condition like
deleted_at IS NULLto your queries. - Restore: You can restore a soft deleted record by setting its
deleted_atfield back to NULL.
Conclusion
Paimon's soft delete feature is a valuable tool for managing data effectively. It provides flexibility in handling data deletion, allowing you to recover lost information and keep a historical record of your data. By understanding how soft delete works and implementing it correctly in your Paimon models, you can ensure that your application handles data deletion efficiently and responsibly.