Thank you, while the answers on Q3 and Q4 were clear enough I still have some problems with the first two questions.
-which entry in the hbase-default.xml allows me to check the size of a tablet? -In hadoop, I used to copy a file to the DFS by doing "bin/hadoop dfs -copyFromLocal filesource fileDFS". Having this file in the DFS I could list it "bin/hadoop dfs -ls" and check its size by doing "bin/hadoop dfs -du fileDFS" But when I create an hbase table, this table does not appear in the DFS. Therefore the latter command gives an error it cannot find the table!! So how can I point to the folder of the table? Regards, CJ On Tue, Sep 1, 2009 at 5:00 PM, Jean-Daniel Cryans <[email protected]>wrote: > Anwers inline. > > J-D > > On Tue, Sep 1, 2009 at 10:53 AM, Xine Jar<[email protected]> wrote: > > Hallo, > > I have a cluster of 6 nodes running hadoop0.19.3 and hbase 0.19.1. I have > > managed to write small programs to test the settings and everything seems > to > > be fine. > > > > I wrote a mapreduce program reading a small hbase table (100 rows, one > > familiy colum, 6 columns) and summing some values. In my opinion the job > is > > slow, it > > is taking 19sec. I would like to look closer what is going, if the table > is > > plit into tablets or not ...Therefore I appreciate if someone can answer > my > > following questions: > > With that size, that's expected. You would be better off scanning your > table directly instead, MapReduce has a startup cost and 19 seconds > isn't that much. > > > > > > > *Q1 -Does the value of "hbase.hregion.max.filesize" in the > > hbase-default.xml indicate the maximum size of a tablet in bytes? > > It's the maximum size of a family (in a region) in bytes. > > > > > Q2- How can I know the size of the hbase table I have created? (I guess > the > > "Describe" command from the shell does not provide it) > > Size as in disk space? You could use the hadoop dfs -du command on > your table's folder. > > > > > Q3- Is there a way to know the real number of tablets constituting my > table? > > In the Master's web UI, click on the name of your table. If you want > to do that programmatically, you can indirectly do it by calling > HTable.getEndKeys() and the size of that array is the number of > regions. > > > > > Q4- Is there a way to get more information on the tablets handeled by > each > > regionserver? (their number, the rows constituting each tablet) * > > In the Master's web UI, click on the region server you want info for. > Getting the number of rows inside a region, for the moment, can't be > done directly (requires doing a scan between the start and end keys of > a region and counting the number of rows you see). > > > > > Thank you for you help, > > CJ > > >
