Using Ping to find out if DB Connection is alive in Golang - go

Question

Is it safe to just ping the database to check if my golang app is still connected or is there a better solution than this? I've read somewhere that we should not use .ping() to determine a connection loss.
Thanks.

Answer 1

I would say Ping() is the way to do it if you need to test the connection separate of running queries probably at program start only.
Normally I just trust in the fact that database/sql will automatically try to reconnect in case if you are executing queries against DB and connection fails. So you could just use Open to check DB connection args are correct and trust query to return an error in case connection is lost.
People say Ping() can cause race conditions but cannot demonstrate me how or provide a suitable alternative where connection test needed.
This is how Gorm (widely used Golang ORM project) does it:
// Send a ping to make sure the database connection is alive.
if d, ok := dbSQL.(*sql.DB); ok {
if err = d.Ping(); err != nil {
d.Close()
}
}
return
https://github.com/jinzhu/gorm

Answer 2

Probably better to execute a simple query and check the result. The Ping() method is safe to use, but is optional to implement by database drivers.
See Ping()

Answer 3

You can ping the database, test it, close the connection, and test it again. Example:
database.go
package main
import (
"log"
"database/sql"
_ "modernc.org/sqlite"
)
func sqliteConnect() (sqliteDB *sql.DB) {
// driver and data source names
sqliteDB, err := sql.Open("sqlite", "./localdatabase.db")
if err != nil {
log.Fatalf("Cannot connect to sqlite DB: %v", err)
}
return sqliteDB
}
database_test.go
package main
import (
"testing"
)
func TestSqliteConnect(t *testing.T) {
db := sqliteConnect()
db.SetMaxIdleConns(0)
t.Run("Ping database", func(t *testing.T) {
if db.Ping() != nil {
t.Errorf("Unable to ping sqlite database ... %v", db.Ping())
}
})
db.Close()
t.Run("Check Connections", func(t *testing.T) {
if db.Stats().OpenConnections != 0 {
t.Errorf("Unable to close database connections ... %v", db.Stats().OpenConnections)
}
})
}