SQL Manager

Simple SQL database resource manager.

Why?

Some SQL database drivers, like Postgres, do not manage their own resources for queries. This results in errors during high traffic when many connections are active at once. This resource manager implements a semaphore to manage resource access and ensure that no more than the max number of connections is active at a time.

This only designed for simple use cases. More advanced applications should look into connection pooling, sharding, etc.

Only tested with the "postgres" Go driver

Usage

Common methods are implemented on the SQLManager struct. Can be used as a drop-in replacement for sql.DB in most simple cases.

package main

import (
	"fmt"
	"sync"

	"github.com/PretendoNetwork/sql-manager"
)

func main() {
	// Match these to your database setup
	driver := "postgres"
	uri := "postgres://username:password@localhost:5432/db"
	maxConnections := 4

	manager, err := sqlmanager.NewSQLManager(driver, uri, maxConnections)
	if err != nil {
		panic(err)
	}
	defer manager.Close()

	_, err = manager.Exec(`CREATE TABLE IF NOT EXISTS test (
		id bigserial PRIMARY KEY
	)`)
	if err != nil {
		panic(err)
	}

	var wg sync.WaitGroup

	// Despite only 4 connections being allowed at once, all 100 calls succeed without issue
	for i := 0; i < 100; i++ {
		wg.Add(1)

		go func() {
			defer wg.Done()

			_, err := manager.Exec("INSERT INTO test DEFAULT VALUES")
			if err != nil {
				panic(err)
			}
		}()
	}

	wg.Wait()

	fmt.Println("Done")
}

Tests

To test 4 environment variables must be set

Name	Description	Example
SQL_MANAGER_TEST_DRIVER	SQL driver name.	postgres
SQL_MANAGER_TEST_URI	SQL database connection string.	postgres://username:password@localhost:5432/db
SQL_MANAGER_TEST_MAX_CONNECTIONS	Number of max connections. Should match your database configuration.	4
SQL_MANAGER_TEST_OPERATIONS	Number of operations to do at once.	100