php - Is unsetting is worth on large arrays? -

i working xml imports. xml files 6 mb max, loop through simplexml arrays , write appropriate records in database nothing difficult , no big worries performance or ram usage. 1 of xml files different. big 145 mb file 50k+ products.

so have few questions:

1) better loop through file same way have done smaller files or product indexes small 3mb file , request other information form remote server 50k times? there no limit on product requests, concerned performance , ram usage here.

my guess requests better idea, want hear more experienced people.

2) second question ram usage , performance. asked other programmer (i intern) , said need unset big array after these operations. truth?

there ton of information insetting variables , arrays, not impact on hardware..

after doing research on question on own found using simplexml on large xml not best idea. xmlreader stream based xml parser looking for.

here quite resource on topic in opinion: http://yashwanthbm.com/parsing-large-xml-documents-in-php/

this answer not answer questions directly, solves problem.