DBResolver for gorm v1. This adds functionality to switch between read and write databases.
go get github.com/go-gorm-v1/dbresolver@v1.0.3 import (
"github.com/go-gorm-v1/dbresolver"
"github.com/jinzhu/gorm"
_ "github.com/mattn/go-sqlite3"
)
func setDatabaseDefaults(db *gorm.DB) {
db.DB().SetMaxIdleConns(MAX_IDLE_CONNECTIONS)
db.DB().SetConnMaxLifetime(CONN_MAX_LIFETIME)
db.DB().SetMaxOpenConns(MAX_OPEN_CONNECTIONS)
db.LogMode(true)
}
func Setup() *dbresolver.Database {
masterDB, err := gorm.Open("sqlite3", "./testdbs/users_write.db")
if err != nil {
log.Fatal("failed to connect to db", err)
}
setDatabaseDefaults(masterDB)
replicaDBs := []*gorm.DB{}
replica, err := gorm.Open("sqlite3", "./testdbs/users_read_a.db")
if err != nil {
log.Fatal("failed to connect to db", err)
}
setDatabaseDefaults(replica)
replicaDBs = append(replicaDBs, replica)
replica, err = gorm.Open("sqlite3", "./testdbs/users_read_b.db")
if err != nil {
log.Fatal("failed to connect to db", err)
}
setDatabaseDefaults(replica)
replicaDBs = append(replicaDBs, replica)
return dbresolver.Register(dbresolver.DBConfig{
Master: masterDB,
Replicas: replicaDBs,
// Policy: &dbresolver.RoundRobalancer{},
// for existing database integration add this
// DefaultMode: &dbresolver.DbWriteMode,
})
}
db := Setup()
db.Raw(`SELECT * FROM users`)It is possible to provide the option to use read or write forcefully.
// Raw By default uses read db
db.Raw(`SELECT * FROM users`)
// Use write db
db.WithMode(dbresolver.DBWriteMode).Raw(`SELECT * FROM users`)
// Use read db
db.WithMode(dbresolver.DBReadMode).Exec(`DELETE FROM users`)It is also possible to set the default mode to write mode.
This uses write mode for all Query methods apart from Where
FindFirstLastTakeCount
dbresolver.DBConfig {
DefaultMode: &dbresolver.DbWriteMode
}By default we have two balancers
// RandomBalancer
dbresolver.DBConfig{
Policy: &dbresolver.RoundRobalancer{}
}
// RandomBalancer
dbresolver.DBConfig{
Policy: &dbresolver.RandomBalancer{}
}You can provide your own load balancer. The Balancer interface is defined as such
type Balancer interface {
Get() int64
}