co-processors in hbase

Observer[Trigger] and Endpoint[Stored Procedures]

Deploy observer :

~]#gradle clean shadowjar #or build jar anyway

hbase>disable 't2'

hbase>alter 't2', 'METHOD'=>'table_att', 'COPROCESSOR'=>'file://<PATH_FILE.JAR>|<PACKAGE.CLASS>|1001'

hbase>enable 't2'

hbase>desc 't2' #To verify deploment.

Undeploy observer:

alter 'dataTbl', 'METHOD'=>'table_att_unset', 'NAME'=>'COPROCESSOR$1'

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Deploy endpoint :

1. Update hbase-site.xml

<property>

  <name>hbase.coprocessor.region.classes</name>

  <value><PACKAGE.CLASS></value>

 </property>

2. Update hbase-env.sh

export HBASE_CLASSPATH=/home/<USER>/RegionObservers-1.0-all.jar

3. Restart hbase

4. Test by running client app

java -cp RegionObservers-1.0-all.jar:lib/guava-18.0.jar:lib/protobuf-java-2.5.0.jar <PACKAGE.CLASS>"

Known issues:

Problem#1:Regionserver terminates due to exception like "jar not found" or "observer class not found" due to incorrect package name or file location while deploying observer.

Soln : add property in hbase-site.xml

<property>

<name>hbase.coprocessor.abortonerror</name>

<value>false</value>

</property>

hbase shell commands, mapreduce

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