Can't save UUID field in PHP script iteration, Laravel, Postgres - laravel

Question

I'm trying to fill already existing models with UUID. And every time it says that UUID is not unique! What a bloody hell! )))
function unique_guid($model){
$guid = com_create_guid();
$table = $model->table;
$db_table = Db::table($table);
$req = $db_table->where("guid", strval($guid));
$instance = $req->first();
if(is_object($instance)){
$guid = unique_guid($model);
return;
}else{
try{
$model->guid = $guid;
$model->save();
sleep(2);
return $guid;
}catch(PDOException $Exception){
$guid = unique_guid($model);
}
}
}
It keeps circling in try/catch block and telling me that it is not unique,
i checked and there is no record with generated UUID.
Also - it brokes at third-fourth iteration, and if i add sleep(5) it works longer - 10 iteration and then brokes.
What in the world can it be?
Laravel 5.5, Postgres 9

Answer 1

Following the Laravel 6.0 official doc, I proceeded the following way:
I added the uuid-ossp extension at database creation. Then, my migrations were like:
use Illuminate\Database\Query\Expression;
...
public function up()
{
Schema::create('my_table', function (Blueprint $table) {
$table->uuid('guid')->primary()->default(new Expression('uuid_generate_v4()'));
...
});
}
I find it a lot more elegant like this.

Answer 2

I believe com_create_guid is not generating unique on every iteration, so please use some increment/prefix value to generated UUID, also if possible use uniqid instead of com_create_guid() uniqid generates id based on the current time in microseconds.
function unique_guid($model,$increment=0){
$guid = uniqid($increment,TRUE);
$table = $model->table;
$db_table = Db::table($table);
$req = $db_table->where("guid", strval($guid));
$instance = $req->first();
if(is_object($instance)){
$guid = unique_guid($model,++$increment);
return;
}else{
try{
$model->guid = $guid;
$model->save();
sleep(2);
return $guid;
}catch(PDOException $Exception){
$guid = unique_guid($model,++$increment);
}
}
}

Answer 3

I think you created function to generate UUID but there is some other better ways to generate UUID. You are using Laravel so you can search packages which are generating UUID.
There is a package I'm suggesting to use.
https://github.com/ramsey/uuid
These types of packages are useful and fully tested by community. So we can trust on them.

Answer 4

You can try like this.. it will check until the guid is really unique
public static function generateUniqueNumber($model = null, $column = null)
{
$num = null;
if ($model) {
$range = $model::all()->pluck('guid')->toArray();
while (in_array($num = com_create_guid(), $range)) {}
}
return $num;
}

Answer 5

I think it's some bug in Postgres 9.3. It inserting two rows at a time on some point of the script. I've eneded with just a migration like that
public function up()
{
DB::statement('CREATE EXTENSION IF NOT EXISTS "uuid-ossp";');
DB::statement('ALTER TABLE feegleweb_octoshop_products ADD COLUMN guid uuid DEFAULT uuid_generate_v4() UNIQUE;');
}
It fill all my rows with unique uuid