Hive Functions

/**
 * Module providing Hive built-in metadata and functions
 * Enables access to Hive UDF, UDAF, and UDTF functions
 */
public class HiveModule implements Module {
    /**
     * Create HiveModule for specific Hive version
     * @param hiveVersion - Hive version string (e.g., "2.3.6")
     */
    public HiveModule(String hiveVersion);
    
    /**
     * Create HiveModule with default latest supported version
     */
    public HiveModule();
    
    /**
     * List all available functions in this module
     * @return Set of function names
     */
    public Set<String> listFunctions();
    
    /**
     * Get function definition by name
     * @param name - Function name to look up
     * @return Optional FunctionDefinition if function exists
     */
    public Optional<FunctionDefinition> getFunctionDefinition(String name);
}

/**
 * Factory for creating HiveModule instances
 * Used by Flink's module loading system
 */
public class HiveModuleFactory implements ModuleFactory {
    /**
     * Get the factory identifier
     * @return "hive" identifier string
     */
    public String factoryIdentifier();
    
    /**
     * Create HiveModule instance from context
     * @param context - Module creation context with options
     * @return New HiveModule instance
     */
    public Module createModule(Context context);
    
    /**
     * Get required configuration options
     * @return Set of required ConfigOption objects
     */
    public Set<ConfigOption<?>> requiredOptions();
    
    /**
     * Get optional configuration options  
     * @return Set of optional ConfigOption objects
     */
    public Set<ConfigOption<?>> optionalOptions();
}

/**
 * Base interface for all Hive function wrappers
 * Marker interface to identify Hive-originated functions
 */
public interface HiveFunction {
    // Marker interface - no methods
}

/**
 * Wrapper for Hive function implementations
 * Provides access to underlying Hive function instance
 */
public class HiveFunctionWrapper<UDFType> implements Serializable {
    /**
     * Create wrapper for Hive function
     * @param className - Hive function class name
     */
    public HiveFunctionWrapper(String className);
    
    /**
     * Create instance of the wrapped function
     * @return New instance of the Hive function
     */
    public UDFType createFunction();
    
    /**
     * Get the class name of the wrapped function
     * @return Fully qualified class name
     */
    public String getClassName();
}

/**
 * Wrapper for Hive Generic UDF functions
 * Handles complex types and object inspection
 */
public class HiveGenericUDF extends ScalarFunction implements HiveFunction {
    /**
     * Create wrapper for Generic UDF
     * @param hiveFunctionWrapper - Wrapper for the Hive function
     * @param hiveShim - Version-specific Hive compatibility shim
     */
    public HiveGenericUDF(HiveFunctionWrapper<GenericUDF> hiveFunctionWrapper, HiveShim hiveShim);
    
    /**
     * Evaluate function with given arguments
     * @param arguments - Function arguments
     * @return Function result
     */
    public Object eval(Object... arguments);
    
    /**
     * Get result type information
     * @param signature - Function signature
     * @return Type information for result
     */
    public TypeInformation<?> getResultType(Class<?>[] signature);
}

/**
 * Wrapper for Hive Simple UDF functions  
 * Handles primitive types and simple objects
 */
public class HiveSimpleUDF extends ScalarFunction implements HiveFunction {
    /**
     * Create wrapper for Simple UDF
     * @param hiveFunctionWrapper - Wrapper for the Hive function
     * @param hiveShim - Version-specific Hive compatibility shim
     */
    public HiveSimpleUDF(HiveFunctionWrapper<UDF> hiveFunctionWrapper, HiveShim hiveShim);
    
    /**
     * Evaluate function with given arguments
     * @param arguments - Function arguments  
     * @return Function result
     */
    public Object eval(Object... arguments);
}

/**
 * Wrapper for Hive Generic UDAF functions
 * Provides aggregation capabilities with accumulators
 */
public class HiveGenericUDAF extends AggregateFunction<Object, GenericUDAFEvaluator.AggregationBuffer> implements HiveFunction {
    /**
     * Create wrapper for Generic UDAF
     * @param funcWrapper - Wrapper for the Hive function
     * @param hiveShim - Version-specific Hive compatibility shim
     */
    public HiveGenericUDAF(HiveFunctionWrapper<GenericUDAF> funcWrapper, HiveShim hiveShim);
    
    /**
     * Create accumulator for aggregation
     * @return New accumulator instance
     */
    public GenericUDAFEvaluator.AggregationBuffer createAccumulator();
    
    /**
     * Get final result from accumulator
     * @param accumulator - Accumulator with aggregated state
     * @return Final aggregation result
     */
    public Object getValue(GenericUDAFEvaluator.AggregationBuffer accumulator);
    
    /**
     * Accumulate value into aggregator
     * @param accumulator - Current accumulator
     * @param input - Input value to accumulate
     */
    public void accumulate(GenericUDAFEvaluator.AggregationBuffer accumulator, Object... input);
    
    /**
     * Retract value from aggregator (for streaming)
     * @param accumulator - Current accumulator
     * @param input - Input value to retract
     */
    public void retract(GenericUDAFEvaluator.AggregationBuffer accumulator, Object... input);
    
    /**
     * Merge two accumulators
     * @param accumulator - Target accumulator
     * @param iterable - Accumulators to merge
     */
    public void merge(GenericUDAFEvaluator.AggregationBuffer accumulator, Iterable<GenericUDAFEvaluator.AggregationBuffer> iterable);
}

/**
 * Wrapper for Hive Generic UDTF functions
 * Provides table-valued function capabilities
 */
public class HiveGenericUDTF extends TableFunction<Row> implements HiveFunction {
    /**
     * Create wrapper for Generic UDTF
     * @param hiveFunctionWrapper - Wrapper for the Hive function
     * @param hiveShim - Version-specific Hive compatibility shim
     */
    public HiveGenericUDTF(HiveFunctionWrapper<GenericUDTF> hiveFunctionWrapper, HiveShim hiveShim);
    
    /**
     * Evaluate function and emit results
     * @param args - Function arguments
     */
    public void eval(Object... args);
    
    /**
     * Get result type information
     * @param signature - Function signature
     * @return Type information for result rows
     */
    public TypeInformation<Row> getResultType(Class<?>[] signature);
}

/**
 * Factory for creating Hive object conversion utilities
 */
public class HiveInspectors {
    /**
     * Get object inspector for Flink data type
     * @param dataType - Flink data type
     * @return Hive ObjectInspector for the type
     */
    public static ObjectInspector getObjectInspector(DataType dataType);
    
    /**
     * Get primitive object inspector for Java class
     * @param clazz - Java class
     * @return PrimitiveObjectInspector for the class
     */
    public static PrimitiveObjectInspector getPrimitiveJavaObjectInspector(Class<?> clazz);
}

/**
 * Interface for converting between Hive and Flink object representations
 */
public interface HiveObjectConversion {
    /**
     * Convert Flink object to Hive representation
     * @param flinkObject - Flink object to convert
     * @return Hive-compatible object
     */
    Object toHiveObject(Object flinkObject);
    
    /**
     * Convert Hive object to Flink representation
     * @param hiveObject - Hive object to convert
     * @return Flink-compatible object
     */
    Object toFlinkObject(Object hiveObject);
}

/**
 * Identity conversion that performs no transformation
 */
public class IdentityConversion implements HiveObjectConversion {
    public Object toHiveObject(Object flinkObject);
    public Object toFlinkObject(Object hiveObject);
}

/**
 * Factory for creating FunctionDefinition from Hive functions
 */
public class HiveFunctionDefinitionFactory {
    /**
     * Create function definition from Hive function
     * @param name - Function name
     * @param functionInfo - Hive function information
     * @param hiveShim - Version-specific compatibility shim
     * @param classLoader - Class loader for function classes
     * @return FunctionDefinition for use in Flink
     */
    public static FunctionDefinition createFunctionDefinitionFromHiveFunction(
        String name,
        FunctionInfo functionInfo, 
        HiveShim hiveShim,
        ClassLoader classLoader
    );
}

import org.apache.flink.table.api.TableEnvironment;
import org.apache.flink.table.module.hive.HiveModule;
import org.apache.flink.table.catalog.hive.HiveCatalog;

// Set up table environment with Hive module
TableEnvironment tableEnv = TableEnvironment.create(EnvironmentSettings.inBatchMode());

// Register Hive catalog
HiveCatalog hiveCatalog = new HiveCatalog("hive", "default", "/opt/hive/conf", null, "2.3.6");
tableEnv.registerCatalog("hive", hiveCatalog);
tableEnv.useCatalog("hive");

// Load Hive module to access Hive functions
HiveModule hiveModule = new HiveModule("2.3.6");
tableEnv.loadModule("hive", hiveModule);

// Use Hive built-in functions in SQL
Table result = tableEnv.sqlQuery(
    "SELECT " +
    "  customer_id," +
    "  CONCAT(first_name, ' ', last_name) as full_name," +  // Hive CONCAT function
    "  REGEXP_REPLACE(phone, '[^0-9]', '') as clean_phone," + // Hive REGEXP_REPLACE
    "  SIZE(order_items) as item_count," +                    // Hive SIZE function
    "  EXPLODE(order_items) as item " +                       // Hive EXPLODE UDTF
    "FROM hive_catalog.customers.customer_orders"
);

result.execute().print();

import org.apache.flink.table.functions.hive.HiveGenericUDF;
import org.apache.flink.table.functions.hive.HiveFunctionWrapper;

// Register custom Hive UDF in Flink
HiveFunctionWrapper<GenericUDF> wrapper = new HiveFunctionWrapper<>("com.example.MyCustomUDF");
HiveGenericUDF customUDF = new HiveGenericUDF(wrapper, hiveShim);

// Register the function in table environment
tableEnv.createTemporaryFunction("my_custom_udf", customUDF);

// Use the custom function in SQL
Table result = tableEnv.sqlQuery(
    "SELECT customer_id, my_custom_udf(customer_data) as processed_data " +
    "FROM hive_catalog.customers.raw_data"
);

// List all available Hive functions
HiveModule hiveModule = new HiveModule("2.3.6");
Set<String> functions = hiveModule.listFunctions();

System.out.println("Available Hive functions:");
functions.stream()
    .sorted()
    .forEach(System.out::println);

// Get specific function definition
Optional<FunctionDefinition> concatDef = hiveModule.getFunctionDefinition("concat");
if (concatDef.isPresent()) {
    System.out.println("Found CONCAT function: " + concatDef.get());
}

public interface Module {
    /**
     * List all functions provided by this module
     * @return Set of function names
     */
    Set<String> listFunctions();
    
    /**
     * Get function definition by name
     * @param name - Function name
     * @return Optional function definition
     */
    Optional<FunctionDefinition> getFunctionDefinition(String name);
}

public interface ModuleFactory extends Factory {
    /**
     * Create module from context
     * @param context - Creation context
     * @return Module instance
     */
    Module createModule(Context context);
}

public abstract class ScalarFunction extends UserDefinedFunction {
    /**
     * Evaluation method for scalar functions
     * @param args - Function arguments
     * @return Function result
     */
    public abstract Object eval(Object... args);
}

public abstract class AggregateFunction<T, ACC> extends UserDefinedFunction {
    /**
     * Create accumulator for aggregation
     * @return New accumulator instance
     */
    public abstract ACC createAccumulator();
    
    /**
     * Get final result from accumulator
     * @param accumulator - Final accumulator state
     * @return Aggregation result
     */
    public abstract T getValue(ACC accumulator);
    
    /**
     * Accumulate input into accumulator
     * @param accumulator - Current accumulator
     * @param input - Input to accumulate
     */
    public abstract void accumulate(ACC accumulator, Object... input);
}

public abstract class TableFunction<T> extends UserDefinedFunction {
    /**
     * Emit result rows from table function
     * @param result - Result to emit
     */
    protected void collect(T result);
    
    /**
     * Evaluation method for table functions
     * @param args - Function arguments
     */
    public abstract void eval(Object... args);
}

public class FlinkHiveUDFException extends RuntimeException {
    public FlinkHiveUDFException(String message);
    public FlinkHiveUDFException(String message, Throwable cause);
}