I do not know why you need use MapFile, could you use SequenceFile instead ?
The MapFile's advantage is its read performance, because it build index on its keys. So its keys must be in order. If you really want to use MapFile, you can first write your data to SequenceFile and then covert it to MapFile. About how to convert SequenceFile to MapFile: 1. Sort the SequenceFile using sort in examples of hadoop 2. create index for the output of the above step. then you get both of the data file and index file You an refer Tom Whilte's book "Hadoop definitive guide" for details about how to convert SequenceFile into MapFile Jeff Zhang On Wed, Oct 28, 2009 at 4:47 PM, lei wang <[email protected]> wrote: > but now, "url" is not in order, must the key be intwritable ? should it > be > comparable ? > How to make sure them in order?sort it first? > I just want to insert the pages for random acess by "url ". > > On Wed, Oct 28, 2009 at 4:26 PM, Jeff Zhang <[email protected]> wrote: > > > Hi Wang, > > > > The keys of MapFile should be in order, so when you add records into > > MapFile, you should make sure you insert them in order > > > > Best Regards, > > > > Jeff Zhang > > > > > > On Wed, Oct 28, 2009 at 4:14 PM, lei wang <[email protected]> > > wrote: > > > > > Hi, friends > > > I need store the web pages(a huge one) in the MapFile of the hadoop, So > i > > > did use the url as the key, and its type is "text", When writring the > > > records into the mapfile, it give an error as "out of order", which > type > > > should I choose to represent the key "url", can anyone give me some > > detail > > > answer, thanks for you help. > > > > > >
