mapreduce - How complex can a Hadoop Map Reduce program be? -

-

two basic general questions, hope can clarify:

  • does every program executed via hadoop has written in map/reduce format?
  • how complex can programs be? (is theoretically possible run program via hadoop?)

your first question:yes because hadoop uses map/reduce model,but can use map function in problem,for example sorting!

your second question:no hadoop can not everything,because use map/reduce model,some program can not resolved map/reduce,like nested program,so companies developed many other program models pregel, dremel , on!


Comments

Post a Comment

Popular posts from this blog

html5 - What is breaking my page when printing? -

-
Image
i have questioner , don't know why when printing it's creating break before first question. live demo (link) i able resolve issue removing fieldset container had wrapped in.. having fieldset element causing of fields grouped together, , since not fit on first page, being pushed second page. removing fieldset element, able firefox print first 2 questions on page 1 identically chrome. it seems not new problem firefox , fieldset not playing nice found old bugzilla ticket 2008 has persisted , still being commented on in 2014 (link) if retaining fieldset important, found solution else came here (link) <script type='text/javascript'> $(window).bind('beforeprint', function(){ $('fieldset').each( function(item) { $(this).replacewith($('<div class="fieldset">' + this.innerhtml + '</div>')); } ) }); $(window).bind(
Read more

c# - must be a non-abstract type with a public parameterless constructor in redis -

-
when save object, got below error must non-abstract type public parameterless constructor in order use parameter 't' in generic type or method 'servicestack.redis.redisclient.store<t>(t) redisclass.getinstnace().store(msg); // error here redisclass.getinstnace().save(); as third party's class, can not edit how save object? could create wrapper around third party object call constructor, store wrapper? e.g. public class mywrapper { public thirdpartyobject thirdpartyinstance { get; set; } public mywrapper() { thirdpartyinstance = new thirdpartyobject("constructors"); } }
Read more

ajax - PHP/JSON Login script (Twitter style) not setting sessions -

-
i'm having trouble getting twitter style login work properly, reason gets stuck at session_register("useremail"); session_register("userpass"); and doesn't redirect after it. if enter wrong account data, works , appropriate error message pops up. this full code: <?php if(empty($_post['email']) || empty($_post['password'])) { die(msg(0,"all fields required")); } if(!(preg_match("/^[\.a-z0-9_\-\+]+[@][a-z0-9_\-]+([.][a-z0-9_\-]+)+[a-z]{1,4}$/", $_post['email']))) die(msg(0,"you haven't provided valid e-mail")); $host="localhost"; $username="root"; $password="x"; $db_name="x"; $tbl_name="x"; mysql_connect("$host", "$username", "$password")or die("cannot connect"); mysql_select_db("$db_name")or die("cannot select db"); $useremail=$_post['email']; $userpass=
Read more