php - PHP: Out of memory error after setting memory limit to -1

Question

I have a script in which I am fetching 725000 records at once and looping through to create array elements. Initially it says memory exhausted. Then, in my script I added-

ini_set('memory_limit', '-1');

After this, it throwing error-

Out of memory (allocated 1585446912) (tried to allocate 52 bytes)

Any suggestion?