HBase Coprocessor

Loading Coprocessors

Static Loading

1.Define the Coprocessor in hbase-site.xml, with a element with a and a sub-element. The should be one of the following:

• hbase.coprocessor.region.classes for RegionObservers and Endpoints.
• hbase.coprocessor.wal.classes for WALObservers.
• hbase.coprocessor.master.classes for MasterObservers.

Value tag must contain the fully-qualified class name of your coprocessor’s implementation class.

For example to load a Coprocessor (implemented in class SumEndPoint.java) you have to create following entry in RegionServer’s 'hbase-site.xml' file (generally located under 'conf' directory):

<name>hbase.coprocessor.region.classes</name>
<value>org.myname.hbase.coprocessor.endpoint.SumEndPoint</value>

2.Put your code on HBase’s classpath. One easy way to do this is to drop the jar (containing you code and all the dependencies) into the lib/ directory in the HBase installation.

3.Restart HBase.

Dynamic Loading

You can also load a coprocessor dynamically, without restarting HBase. This may seem preferable to static loading, but dynamically loaded coprocessors are loaded on a per-table basis, and are only available to the table for which they were loaded. For this reason, dynamically loaded tables are sometimes called Table Coprocessor.

In addition, dynamically loading a coprocessor acts as a schema change on the table, and the table must be taken offline to load the coprocessor. Otherwise may cause RIT (Regions in Transition)

---

EndPointCoprocessor prefer static loading than dynamic loading.