MySQL large requests don't work in AJAX and need LIMIT, while working in straight PHP -

i have mysql table can contain 500 000 rows , calling them on site without limit clause; when without ajax, works normally, ajax , again without setting limit, no data returned. checked ajax code , there no mistake there. thing , when write limit, example 45 000 , works perfectly; above this, ajax returns nothing.

with limit

witohut limit :

can ajax issue because found nothing similar on web or else?

edit

here sql request

select ans.*, quest.inversion, t.wave_id, t.region_id, t.branch_id, quest.block, quest.saleschannelid, b.division, b.regionsid, quest.yes, quest.no cms_vtb ans  left join cms_vtb_question quest on ans.question_id=quest.id  left join cms_task t on t.id=ans.task_id left join cms_wave w on w.id=t.wave_id  left join cms_branchemployees b on b.id=t.branchemployees_id t.publish='1' , t.concurent_id='' , ans.answer<>'3' , w.publish='1' , quest.questhide<>1 order t.concurent_id desc limit 44115 

the php :

var url='&module=ajax_typespace1&<?=$base_url?>';  $.ajax({      url: 'moduls_ajax.php?'+url,      cache: false,      datatype:'html',         success: function(data)      {         $("#result").html(data);      }  }); 

apparently server error, adding ini_set('memory_limit', '2048m'); helped lot