albertwidi / sqlt

Sqlx wrapper with round-robin load-balancing feature

sqlt

Sqlt is a wrapper package for jmoiron/sqlx

This wrapper build based on tsenart/nap master-slave and its load-balancing configuration with some modification

Since this package is just a wrapper, you can use it 100% like nap but with the taste of sqlx

Usage

To connect to database, you need an appended connection string with ; delimeter, but there is some notes:

• First connection will always be considered as master connection
• Another connection will be considered as slave

databaseCon := "con1;" + "con2;" + "con3"
db, err := sqlt.Open("postgres", databaseCon)

Or

databaseCon := "con1"
db, err := sqlt.Open("postgres", databaseCon)

Query Example:

row := db.QueryRow(query, args)

rows, err := db.Query(query, args)

err := db.Select(&struct, query, args)

err := db.Get(&struct, query, args)

preapre and preparex for sql and sqlx are supported

use preparex to enable ScanStruct

statement := db.Prepare(query)
rows, err := statement.Query(param)
row := statement.QueryRows(param).Scan(&var)

statement := db.Preparex(query)
rows, err := statement.Query(param)
row := statement.QueryRows(param).ScanStruct(&struct)

Complete example:

package main

// lib/pq or go-sql-driver needed to import database driver
import (
    _"github.com/lib/pq"
    _ "github.com/go-sql-driver/mysql"
    "github.com/albert-widi/sqlt"
    "log"
)

func main() {
    masterDSN := "user:password@tcp(master_ip:master_port)/database_name"
    slave1DSN := "user:password@tcp(slave_ip:slave_port)/database_name"
    slave2DSN := "user:password@tcp(slave2_ip:slave2_port)/database_name"

    dsn := masterDSN + ";" + slave1DSN + ";" + slave2DSN
    
    db, err = sqlt.Open("mysql", dsn)
    if err != nil {
      log.Println("Error ", err.Error())
    }
    
    // do something using db connection
}

Heartbeat/Watcher

SQLT provide a mechanism to switch between slaves if something bad happen. If no slaves is available then all connection will go to master.

The watcher will auto-reconnect to your slaves if possible and start to load-balancing itself.

To watch all slaves connection, use DoHeartbeat. This will ping your database every second and make auto-reconnect if needed.

databaseCon := "con1;" + "con2;" + "con3"
db, err := sqlt.Open("postgres", databaseCon)

if err != nil {
  return err
}

//this will automatically ping the database and watch the connection
db.DoHeartBeat()

Don't forget to stop the heartbeat when your application stop, because it(goroutine) will most likely leak if you forgot to close it.

db.StopBeat()

Database status

You can also get the database status, for example:

databaseCon := "con1;" + "con2;" + "con3"
db, err := sqlt.OpenWithName("postgres", databaseCon, "order")

if err != nil {
  return err
}

//this will automatically ping the database and watch the connection
db.DoHeartBeat()

//this will return database status in JSON
status, _ := db.GetStatus()

Output:

DbStatus {
  Name:       "order",
  Connected:  true,
  LastActive: "21 September 2016",
  Error:      nil,
}

---

3rd party references:

• https://github.com/jmoiron/sqlx
• https://github.com/tsenart/nap