Inline. J-D
On Tue, Sep 1, 2009 at 1:05 PM, Xine Jar<[email protected]> wrote: > Thank you, > > while the answers on Q3 and Q4 were clear enough I still have some problems > with the first two questions. Good > > -which entry in the hbase-default.xml allows me to check the size of a > tablet? Those are configuration parameters, not commands. A region will split when a family gets that size. See http://wiki.apache.org/hadoop/Hbase/HbaseArchitecture#hregion for more info on splitting. > > -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? Just make sure the table is flushed to disk, the writes are kept in memory as described in the link I pasted for the previous question. You can force that by going in the shell and issuing "flush 'table'" where table replaced with the name of your 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 >> > >> >
