array_search() with array_column() is very slow, how can I speed this up?-CodePudding

Hi all I have the following function (With the internal stuff cut out) :

    /**
     * @param int $lastSyncTimeStampLocal
     * @return void
     */
    protected function compareData(int $lastSyncTimeStampLocal): void
    {
        $time_start = microtime(true);

        foreach ($this->localData as $row) {
            $key = array_search($row['uuid'], array_column($this->masterData, 'uuid'));
        }

        $time_end = microtime(true);

        $execution_time = ($time_end - $time_start)/60;

    }

This function is to compare 2 sets of data. The problem is the array_search is very slow with large amount of data.

eg if $this->localData and $this->masterData both contains 10000 records then this functions takes approximately 30 seconds to complete. I am wondering if there is an alternative/ any thing I can change to make this a lot faster? Note uuid is a string like 'dkdue29u29dbiyedh92dye'

Thanks for any help

CodePudding user response：

Difficult to test with large result sets, but I hope this works out.

First thing is not to repeat any operation in the loop if you can. So the array_column call is moved outside the loop.

Rather than using array_search(), using the values as the keys means you can just do an array reference. BUT using array_flip() on it's own would mean that you would end up with the last occurrence of rather than the first one. So this code uses array_reverse() followed by array_flip() to mean that you end up with a array keyed by the uuid with the value being the position in the array.

(May be worth printing out the $uuids array to see what I mean by this).

Then inside the loop, you just use a straight forward array access with $uuids[$row['uuid']] and use ?? -1 which sets -1 when the value is not present.

$uuids = array_flip(array_reverse(array_column($this->masterData, 'uuid')));
foreach ($this->localData as $row) {
    $key = $uuids[$row['uuid']] ?? -1;
}