J-D,
There's an alternative... He could write a M/R that takes the input from a scan() , do something, reduce() and then output the reduced set back to hbase in the form of a temp table. (Even an in memory temp table) and then at the end pull the data out in to a hash table? In theory this should be possible, but I haven't had time to play with in memory tables.... No? Thx -Mike > Date: Mon, 5 Apr 2010 09:57:02 -0700 > Subject: Re: hbase mapreduce scan > From: jdcry...@apache.org > To: hbase-user@hadoop.apache.org > > You want to put the result in a HashMap? MapReduce is a batch > processing framework that runs multiple parallel JVMs over a cluster > of machines so I don't see how you could simply output in a HashMap > (unless you don't mind outputting on disk, then reading it back into a > HashMap). > > So I will guess that you want to do a live query against HBase, here > MR won't help you since that is meant for bulk processing which > usually takes more than a minute. > > What you want to use is a Scan, using HTable. The unit tests have tons > of example on how to use a scanner, look in the > org.apache.hadoop.hbase.client package, so will find what you need. > The main client package also contains some examples > http://hadoop.apache.org/hbase/docs/r0.20.3/api/org/apache/hadoop/hbase/client/package-summary.html > > J-D > > On Sun, Apr 4, 2010 at 11:18 AM, Jürgen Jakobitsch <jakobits...@punkt.at> > wrote: > > hi, > > > > i'm totally new to hbase and mapreduce and could really need some > > pointer into the right direction for the following situation. > > > > i managed to run a basic mapreduce example - analog to Export.java > > in the hbase.mapreduce package. > > > > what i need to achieve is the following : > > > > do a map/reduce scan on a hbase table and put the results > > into a HashMap. > > > > could someone point me to an example. > > > > any help really appreciated > > > > wkr turnguard.com/turnguard > > > > -- > > punkt. netServices > > ______________________________ > > Jürgen Jakobitsch > > Codeography > > > > Lerchenfelder Gürtel 43 Top 5/2 > > A - 1160 Wien > > Tel.: 01 / 897 41 22 - 29 > > Fax: 01 / 897 41 22 - 22 > > > > netServices http://www.punkt.at > > > > _________________________________________________________________ Hotmail has tools for the New Busy. Search, chat and e-mail from your inbox. http://www.windowslive.com/campaign/thenewbusy?ocid=PID28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_1
