To extend Apache Drill, implement custom functions, storage plugins, and query operators as follows:
1. Custom Functions: Create a Java class extending Drill’s built-in functions (e.g., ScalarFunction or AggregateFunction). Annotate the class with @FunctionTemplate and define the function logic in the “eval” method. Package the compiled class into a JAR file and place it in the /jars/3rdparty directory.
2. Storage Plugins: Implement a custom storage plugin by creating a Java class that extends AbstractStoragePlugin. Define the required methods such as getPhysicalOptimizerRules(), getGroupScan(), and createNewTable(). Register the new plugin in the Drill configuration file (storage-plugins-override.conf) and restart Drill to load the plugin.
3. Query Operators: Develop custom query operators by implementing interfaces like PhysicalOperator, Prel, and Prule. Extend existing classes like SinglePrel or AbstractUnaryPrel for unary operators. Override necessary methods like getPhysicalOperator() and match(). Add the operator rule to the optimizer ruleset in Drill’s source code and recompile Drill.
