It concludes that volume is the most tackled aspect and many works leverage Hadoop MapReduce to deal with volume
[21,40,41,22]. More and more, unlike velocity, web and social media informality and uncertainty are addressed by scientists.
We see that uncertainty can be handled manually (Ripple Down Rules [44]) or automatically (identification and/orisolation of inconsistencies [88]). About velocity, gazetteers and knowledge bases must be continually updated [88,45] and data processed periodically [43,42].