On Thu, Jul 26, 2012 at 7:16 AM, Alex Baranau <alex.barano...@gmail.com>wrote:
> Looks like you have only one region in your table. Right? > > If you want your writes to be distributed from the start (without waiting > for HBase to fill table enough to split it in many regions), you should > pre-split your table. In your case you can pre-split table with 10 regions > (just an example, you can define more), with start keys: "", "1", "2", ..., > "9" [1]. > > Thanks a lot! Is there any specific best practice on how many regions one should split a table into? > Btw, since you are salting your keys to achieve distribution, you might > also find this small lib helpful which implements most of the stuff for you > [2]. > > I'll take a look > Hope this helps. > > Alex Baranau > ------ > Sematext :: http://blog.sematext.com/ :: Hadoop - HBase - ElasticSearch - > Solr > > [1] > > byte[][] splitKeys = new byte[9][]; > // the first region starting with empty key will be created > automatically > for (int i = 1; i < splitKeys.length; i++) { > splitKeys[i] = Bytes.toBytes(String.valueOf(i)); > } > > HBaseAdmin admin = new HBaseAdmin(conf); > admin.createTable(tableDescriptor, splitKeys); > > [2] > https://github.com/sematext/HBaseWD > > http://blog.sematext.com/2012/04/09/hbasewd-avoid-regionserver-hotspotting-despite-writing-records-with-sequential-keys/ > > On Wed, Jul 25, 2012 at 7:54 PM, Mohit Anchlia <mohitanch...@gmail.com > >wrote: > > > On Wed, Jul 25, 2012 at 6:53 AM, Alex Baranau <alex.barano...@gmail.com > > >wrote: > > > > > Hi Mohit, > > > > > > 1. When talking about particular table: > > > > > > For viewing rows distribution you can check out how regions are > > > distributed. And each region defined by the start/stop key, so > depending > > on > > > your key format, etc. you can see which records go into each region. > You > > > can see the regions distribution in web ui as Adrien mentioned. It may > > also > > > be handy for you to query .META. table [1] which holds regions info. > > > > > > In cases when you use random keys or when you just not sure how data is > > > distributed in key buckets (which are regions), you may also want to > look > > > at HBase data on HDFS [2]. Since data is stored for each region > > separately, > > > you can see the size on the HDFS each one occupies. > > > > > > I did a scan and the data looks like as pasted below. It appears all my > > writes are going to just one server. My keys are of this type > > [0-9]:[current timestamp]. Number between 0-9 is generated randomly. I > > thought by having this random number I'll be able to place my keys on > > multiple nodes. How should I approach this such that I am able to use > other > > nodes as well? > > > > > > > > SESSION_TIMELINE1,,1343074465420.5831bbac53e59 column=info:regioninfo, > > timestamp=1343170773523, value=REGION => {NAME => > > 'SESSION_TIMELINE1,,1343074465420.5831bbac53e591c609918c0e2d7da7 > > 1c609918c0e2d7da7bf. bf.', STARTKEY => '', > > ENDKEY => '', ENCODED => 5831bbac53e591c609918c0e2d7da7bf, TABLE => > {{NAME > > => 'SESSION_TIMELINE1', FAMILIES => [{NAM > > E => 'S_T_MTX', > BLOOMFILTER > > => 'NONE', REPLICATION_SCOPE => '0', COMPRESSION => 'GZ', VERSIONS => > '1', > > TTL => '2147483647', BLOCKSIZE => ' > > 65536', IN_MEMORY => > > 'false', BLOCKCACHE => 'true'}]}} > > SESSION_TIMELINE1,,1343074465420.5831bbac53e59 column=info:server, > > timestamp=1343178912655, value=dsdb3.:60020 > > 1c609918c0e2d7da7bf. > > > > > 2. When talking about whole cluster, it makes sense to use cluster > > > monitoring tool [3], to find out more about overall load distribution, > > > regions of multiple tables distribution, requests amount, and many more > > > such things. > > > > > > And of course, you can use HBase Java API to fetch some data of the > > cluster > > > state as well. I guess you should start looking at it from HBaseAdmin > > > class. > > > > > > Alex Baranau > > > ------ > > > Sematext :: http://blog.sematext.com/ :: Hadoop - HBase - > ElasticSearch > > - > > > Solr > > > > > > [1] > > > > > > hbase(main):001:0> scan '.META.', {LIMIT=>1, STARTROW=>"mytable,,"} > > > ROW > > > COLUMN+CELL > > > > > > > > > mytable,,1341279432683.8fd61cd7ef426d2f233a4cd7e8b73845. > > > column=info:regioninfo, timestamp=1341279432625, value=REGION => {NAME > > => > > > 'mytable,,1341279432683.8fd61cd7ef426d2f233a4cd7e8b73845.', STARTKEY => > > > 'chicago', ENDKEY => 'new_york', ENCODED => > > > fd61cd7ef426d2f233a4cd7e8b73845, TABLE => {{NAME => 'mytable', FAMILIES > > => > > > [{NAME => 'job', BLOOMFILTER => 'NONE', REPLICATION_SCOPE => '0', > > > COMPRESSION => 'NONE', VERSIONS => '1', TTL => '2147483647', BLOCKSIZE > => > > > '65536', IN_MEMORY => 'false', BLOCKCACHE => 'true'}]}} > > > > > > > > > > > > mytable,,1341279432683.8fd61cd7ef426d2f233a4cd7e8b73845. > > > column=info:server, timestamp=1341279432673, value=myserver:60020 > > > > > > > > > mytable,,1341279432683.8fd61cd7ef426d2f233a4cd7e8b73845. > > > column=info:serverstartcode, timestamp=1341279432673, > > value=1341267474257 > > > > > > > > > 1 row(s) in 0.1980 seconds > > > > > > [2] > > > > > > ubuntu@ip-10-80-47-73:~$ sudo -u hdfs hadoop fs -du /hbase/mytable > > > Found 130 items > > > 3397 hdfs://hbase.master/hbase/mytable > > > /02925d3c335bff7e273f392324f16dca > > > 2682163424 hdfs://hbase.master/hbase/mytable > > > /03231b8ae2b73317c4858b1a85c09ad2 > > > 1038862956 hdfs://hbase.master/hbase/mytable > > > /04f911571593e931a9a3d9e2a6616236 > > > 1039181555 hdfs://hbase.master/hbase/mytable > > > /0a177633196cae7b158836181d69dc0f > > > 1076888812 hdfs://hbase.master/hbase/mytable > > > /0d52fc477c41a9a236803234d44c7c06 > > > > > > [3] > > > You can get data from JMX directly using any tool you like or use: > > > * Ganglia > > > * SPM monitoring ( > > > http://sematext.com/spm/hbase-performance-monitoring/index.html) > > > * others > > > > > > > > > On Wed, Jul 25, 2012 at 1:59 AM, Adrien Mogenet < > > adrien.moge...@gmail.com > > > >wrote: > > > > > > > From the web-interface, you can have such statistics when viewing the > > > > details of a table. > > > > You can also develop your own "balance viewer" through the HBase API > > > (list > > > > of RS, regions, storeFiles, their size, etc.) > > > > > > > > On Wed, Jul 25, 2012 at 7:32 AM, Mohit Anchlia < > mohitanch...@gmail.com > > > > >wrote: > > > > > > > > > Is there an easy way to tell how my nodes are balanced and how the > > rows > > > > are > > > > > distributed in the cluster? > > > > > > > > > > > > > > > > > > > > > -- > > > > Adrien Mogenet > > > > 06.59.16.64.22 > > > > http://www.mogenet.me > > > > > > > > > > > > > > > > -- > > > Alex Baranau > > > ------ > > > Sematext :: http://blog.sematext.com/ :: Hadoop - HBase - > ElasticSearch > > - > > > Solr > > > > > > > > > -- > Alex Baranau > ------ > Sematext :: http://blog.sematext.com/ :: Hadoop - HBase - ElasticSearch - > Solr >
