Question

I am trying to assign a defined random order to a table of over 10000+ records. I have a function utilizing a start date and adding 1 second to each consecutive date, assigned randomly. Then I could sort by the random assigned date. My function worked fine with 50 records, but fails with 10000+ records.

It sets correct dates for about 9000 records, but 1146 records get assigned 0 (1969-12-31 19:00:00) Any help getting this or something similar to work would be appreciated.

function randomize(){
  $count = $this->Application->find('count');
  $order = range(0, $count-1); // Array of numbers 0 to count-1
  $startDate = strtotime('December 13, 2011 0:00:00');
  shuffle($order); // scramble array of numbers
  $Applications = $this->Application->find('all');
  set_time_limit(0);
  foreach($Applications as $app){
    $this->Application->id = $app['Application']['id'];
    $this->Application->saveField('order', date('Y-m-d H:i:s', $startDate + $order[$this->Application->id]));
  }
  set_time_limit(30);
}

Update: I am using MySQL database but need a permanent state for 1 randomization, not repeated randomization as per ORDER BY RAND(). I also updated the code (see above) to reduce overhead, and increased memory in php.ini from 128M to 256M. With the code change the bad dates are no longer 0 but the same as $startDate indicating it may be an issue with the $order array of numbers.

Answer 1

Questions:

Are you sure you’re using the proper date format there?

Why a start date to randomize? Take the date as a fixed number, as you’re doing (X in this case): If you do X + givenOrderNumber for each record then the order will be defined by givenOrderNumber… so why the unnecessary addition?

I’ve got the query I understand you’re looking for here:

set @num = 0;
select *,
  date_add('2011-12-13 00:00:00', interval @num := @num + 1 second) as newOrder
from table1
order by newOrder

Example

It sorts the records by a date which is incremented by one each time. Now if you want to use the application id cheat:

select *,
  date_add('2011-12-13 00:00:00', interval id second) as newOrder
from table1
order by newOrder

Example

However, whether this is useful or not for you… it seems to be unnecessary.

Hope this helps.