Java 示例:定义参数

以下代码片段演示了将单个参数添加到 Java add2ints UDSF 示例。getParameterType() 函数定义了名为 constant 的单个整数参数。

package com.mycompany.example;
import com.vertica.sdk.*;
public class Add2intsWithConstantFactory extends ScalarFunctionFactory
{
    @Override
    public void getPrototype(ServerInterface srvInterface,
                             ColumnTypes argTypes,
                             ColumnTypes returnType)
    {
        argTypes.addInt();
        argTypes.addInt();
        returnType.addInt();
    }

    @Override
    public void getReturnType(ServerInterface srvInterface,
                              SizedColumnTypes argTypes,
                              SizedColumnTypes returnType)
    {
        returnType.addInt("sum");
    }

    // Defines the parameters for this UDSF. Works similarly to defining
    // arguments and return types.
    public void getParameterType(ServerInterface srvInterface,
                              SizedColumnTypes parameterTypes)
    {
        // One INTEGER parameter named constant
        parameterTypes.addInt("constant");
    }

    @Override
    public ScalarFunction createScalarFunction(ServerInterface srvInterface)
    {
        return new Add2intsWithConstant();
    }
}

有关定义参数时可调用的特定于数据类型的方法的完整列表,请参阅 SizedColumnTypes 的 Vertica Java SDK 条目。