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Apache Accumulo Classpath Example

This example shows how to use per table classpaths. The example leverages a test jar which contains a Filter that suppresses rows containing "foo". The example shows configuring a table to load classes from the jar using the URL-based context class loader. Note that the FooFilter.jar is located within the Accumulo source distribution.

Create a namespace and table

root@uno> createnamespace examples
root@uno> createtable examples.nofoo

The following command configures the table to load classes from the jar URL.

root@uno examples.nofoo> config -t examples.nofoo -s table.class.loader.context=file:///path/to/accumulo/test/src/main/resources/org/apache/accumulo/test/FooFilter.jar

The following command configures an iterator that's in FooFilter.jar

root@uno examples.nofoo> setiter -n foofilter -p 10 -scan -minc -majc -class org.apache.accumulo.test.FooFilter
Filter accepts or rejects each Key/Value pair
----------> set FooFilter parameter negate, default false keeps k/v that pass accept method, true rejects k/v that pass accept method: false

The commands below show the filter is working.

root@uno examples.nofoo> insert foo1 f1 q1 v1
root@uno examples.nofoo> insert noo1 f1 q1 v2
root@uno examples.nofoo> scan
noo1 f1:q1 []    v2
root@uno examples.nofoo>

Below, an attempt is made to add the FooFilter to a table that's not configured to load classes from the jar URL. This fails until the table is configured with the jar URL.

root@uno examples.nofoo> createtable examples.nofootwo
root@uno examples.nofootwo> setiter -n foofilter -p 10 -scan -minc -majc -class org.apache.accumulo.test.FooFilter
    2013-05-03 12:49:35,943 [shell.Shell] ERROR: org.apache.accumulo.shell.ShellCommandException: Command could 
not be initialized (Unable to load org.apache.accumulo.test.FooFilter; class not found.)
root@uno examples.nofootwo> config -t examples.nofootwo -s table.class.loader.context=file:///path/to/accumulo/test/src/main/resources/org/apache/accumulo/test/FooFilter.jar
root@uno examples.nofootwo> setiter -n foofilter -p 10 -scan -minc -majc -class org.apache.accumulo.test.FooFilter
Filter accepts or rejects each Key/Value pair
----------> set FooFilter parameter negate, default false keeps k/v that pass accept method, true rejects k/v that pass accept method: false