Imagine you have to get track of some kind of traffic, for example, "ad impressions"; lets supose that you have millions of those hits; you will have to have a few servers to receive the notifications of the impression of an ad. After the end of the day, you will have that info across a bunch of servers; mostly you will have a record of each impression indicating the Identifier (id) of the Ad. To this info to become useful, you will have to agregate it; for example to know which is the Ad with most impressions. You will have to iterate over all servers and MAP the info into one place; now that you have all the info, you will have to REDUCE it; so you will have one record per Ad identifier indicating the TOTAL impressions of that day. That's the basic idea. It's like aftermath of "Divide and Conquer". Hope this will be useful. Cheers. On 22 October 2010 13:27, Artur Ejsmont <ejsmont.artur@xxxxxxxxx> wrote: > hehe .... sorry but this does not help :-) i can google for wikipedia > definitions. > > I was hoping for some really good articles/examples that would put it > into enough context. I would like to have good idea when it could be > useful. > > So far had no luck with that. Its like with design patterns ... people > who dont understand them should not write articles trying to explain > them to others :P > > Art > > On 22 October 2010 15:29, AndrÃs G. MontaÃez <andresmontanez@xxxxxxxxx> wrote: >> Hi Artur, >> >> Here is an article on wikipedia: http://en.wikipedia.org/wiki/MapReduce >> >> And here are the native implementations in php: >> http://www.php.net/manual/en/function.array-map.php >> http://www.php.net/manual/en/function.array-reduce.php >> >> The basic idea is to gather a lot of data, from several nodes, and >> "map" them togheter; >> then, assuming a lot of this data is repeated across the dataset, we >> "reduce" them. >> >> >> Cheers. >> >> On 22 October 2010 12:14, Artur Ejsmont <ejsmont.artur@xxxxxxxxx> wrote: >>> Hi there guys and girls >>> >>> Have anyone came across any reasonable explanation / articles on how >>> hadoop and map reduce work in practice? >>> >>> i have read a few articles now and then and i must say i am puzzled >>> .... am i stupid or they just cant find an easy way to explain it? :P >>> >>> What i would hope for is explanation on simple example of application >>> with some code samples preferably. >>> >>> anyone good at it here? >>> >>> cheers >>> >>> -- >>> PHP Database Mailing List (http://www.php.net/) >>> To unsubscribe, visit: http://www.php.net/unsub.php >>> >>> >> >> >> >> -- >> AndrÃs G. MontaÃez >> Zend Certified Engineer >> Montevideo - Uruguay >> > > > > -- > Visit me at: > http://artur.ejsmont.org/blog/ > -- AndrÃs G. MontaÃez Zend Certified Engineer Montevideo - Uruguay -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
