"but since hbase returns the values sorted" You are right. I just wanted to highlight the subtlety that you are essentially relying on the external mechanism for the desired feature (sorting) rather than the collection/container itself (as in TreeMap.) In this case, it is most probably redundant and you can use LinkedHashMap to avoid resorting.
Regards, Shahab On Fri, Sep 13, 2013 at 12:50 PM, John <johnnyenglish...@gmail.com> wrote: > Yes, thats a good point @ Shahab, but since hbase returns the values sorted > everything shlould be fine and I can use the LinkedHashMap. > > Thanks to both of you! > > > 2013/9/13 Shahab Yunus <shahab.yu...@gmail.com> > > > "But I used > > a LinkedHashMap insead. Do you knows whats the better choice? TreeMap > > or LinkedHashMap?" > > > > If you are asking from functionality perspective then there is a > difference > > between them that LinkedHashMap maintains the order in which items were > > entered in the map. So if they were entered in the correct order then you > > are fine but for any reason if they are not entered in the correct order > > that you want (i.e. some kind of sort order) then you will not be able to > > get your desired order. > > > > TreeMap on the other handle, makes sure that the ordering is > > right according to the natural ordering of the elements. Gives you more > > security in terms of what you want. > > > > Regards, > > Shahba > > > > > > On Fri, Sep 13, 2013 at 12:29 PM, John <johnnyenglish...@gmail.com> > wrote: > > > > > Hi, thanks for your quick answer! I figured it out by my self since the > > > mailing server was down the last 2hours?! Btw. I did option 1. But I > > used > > > a LinkedHashMap insead. Do you knows whats the better choice? TreeMap > > > or LinkedHashMap? > > > > > > Anyway thanks :) > > > > > > > > > 2013/9/13 Pradeep Gollakota <pradeep...@gmail.com> > > > > > > > Thats a great observation John! The problem is that HBaseStorage maps > > > > columns families into a HashMap, so the sort ordering is completely > > lost. > > > > > > > > You have two options: > > > > > > > > 1. Modify HBaseStorage to use a SortedMap data structure (i.e. > TreeMap) > > > and > > > > use the modified HBaseStorage. (or make it configurable) > > > > 2. Since you convert the map to a bag, you can sort the bag in a > nested > > > > foreach statement. > > > > > > > > I prefer option 1 myself because it would be more performant than > > option > > > 2. > > > > > > > > > > > > On Fri, Sep 13, 2013 at 7:31 AM, John <johnnyenglish...@gmail.com> > > > wrote: > > > > > > > > > I have created a HBase Table in the hbase shell and added some > data. > > In > > > > > http://hbase.apache.org/book/dm.sort.html is written that the > > datasets > > > > are > > > > > first sorted by the rowkey and then the column. So I tried > something > > in > > > > the > > > > > HBase Shell: http://pastebin.com/gLVAX0rJ > > > > > > > > > > Everything looks fine. I got the right order a -> c -> d like > > expected. > > > > > > > > > > Now I tried the same with Apache Pig in Java: > > > > http://pastebin.com/jdTpj4Fu > > > > > > > > > > I got this result: > > > > > > > > > > (key1,[c#val,d#val,a#val]) > > > > > > > > > > So, now the order is c -> d -> a. That seems a little odd to me, > > > > shouldn't > > > > > it be the same like in HBase? It's important for me to get the > right > > > > order > > > > > because I transform the map afterwards into a bag and then join it > > with > > > > > other tables. If both inputs are sorted I could use a merge join > > > without > > > > > sorting these two datasets. So does anyone know how it is possible > to > > > get > > > > > the sorted map (or bag) of the columns? > > > > > > > > > > > > > > > thanks > > > > > > > > > > > > > > >
