Apache Presto - 自定函式應用程式

建立一個 Maven 專案，以開發 Presto 自定函式。

SimpleFunctionsFactory.java

建立 SimpleFunctionsFactory 類，以實現 FunctionFactory 介面。

package com.tutorialspoint.simple.functions;  

import com.facebook.presto.metadata.FunctionFactory; 
import com.facebook.presto.metadata.FunctionListBuilder; 
import com.facebook.presto.metadata.SqlFunction; 
import com.facebook.presto.spi.type.TypeManager;  
import java.util.List;  

public class SimpleFunctionFactory implements FunctionFactory { 
   
   private final TypeManager typeManager;  
   public SimpleFunctionFactory(TypeManager typeManager) { 
      this.typeManager = typeManager; 
   }  
    @Override 
    
   public List<SqlFunction> listFunctions() { 
      return new FunctionListBuilder(typeManager) 
      .scalar(SimpleFunctions.class) 
      .getFunctions(); 
   } 
}

SimpleFunctionsPlugin.java

建立一個 SimpleFunctionsPlugin 類，以實現 Plugin 介面。

package com.tutorialspoint.simple.functions;  

import com.facebook.presto.metadata.FunctionFactory; 
import com.facebook.presto.spi.Plugin; 
import com.facebook.presto.spi.type.TypeManager; 
import com.google.common.collect.ImmutableList;  
import javax.inject.Inject; 
import java.util.List; 
import static java.util.Objects.requireNonNull;  

public class SimpleFunctionsPlugin implements Plugin {  
   private TypeManager typeManager; 
   @Inject 
   
   public void setTypeManager(TypeManager typeManager) { 
      this.typeManager = requireNonNull(typeManager, "typeManager is null”); 
      //Inject TypeManager class here 
   }  
   @Override 
   
   public <T> List<T> getServices(Class<T> type){ 
      if (type == FunctionFactory.class) { 
         return ImmutableList.of(type.cast(new SimpleFunctionFactory(typeManager))); 
      } 
      return ImmutableList.of(); 
   } 
}

新增資原始檔

建立一個在實現包中指定的資原始檔。

(com.tutorialspoint.simple.functions.SimpleFunctionsPlugin)

現在，移動到資原始檔位置 @ /path/to/resource/

然後新增更改，

com.facebook.presto.spi.Plugin 

pom.xml

將以下依賴關係新增到 pom.xml 檔案。

<?xml version = "1.0"?> 
<project xmlns = "http://maven.apache.org/POM/4.0.0"  
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
 xsi:schemaLocation = "http://maven.apache.org/POM/4.0.0  
    http://maven.apache.org/xsd/maven-4.0.0.xsd">  
   
   <modelVersion>4.0.0</modelVersion> 
   <groupId>com.tutorialspoint.simple.functions</groupId> 
   <artifactId>presto-simple-functions</artifactId>  
   <packaging>jar</packaging>  
   <version>1.0</version>
   <name>presto-simple-functions</name>
   <description>Simple test functions for Presto</description> 
   <properties> 
      <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   </properties>  
   <dependencies> 
      <dependency> 
         <groupId>com.facebook.presto</groupId> 
         <artifactId>presto-spi</artifactId>
         <version>0.149</version> 
      </dependency>  
      <dependency> 
         <groupId>com.facebook.presto</groupId> 
         <artifactId>presto-main</artifactId> 
         <version>0.149</version> 
      </dependency>  
      <dependency> 
         <groupId>javax.inject</groupId> 
         <artifactId>javax.inject</artifactId> 
         <version>1</version> 
      </dependency>  
      <dependency> 
         <groupId>com.google.guava</groupId> 
         <artifactId>guava</artifactId> 
         <version>19.0</version> 
      </dependency> 
   </dependencies>  
   <build> 
      <finalName>presto-simple-functions</finalName>  
      <plugins>  
      <!-- Make this jar executable --> 
         <plugin> 
            <groupId>org.apache.maven.plugins</groupId> 
            <artifactId>maven-jar-plugin</artifactId> 
            <version>2.3.2</version> 
         </plugin> 
      </plugins> 
   </build> 
</project>

SimpleFunctions.java

使用 Presto 屬性建立 SimpleFunctions 類。

package com.tutorialspoint.simple.functions;  

import com.facebook.presto.operator.Description; 
import com.facebook.presto.operator.scalar.ScalarFunction; 
import com.facebook.presto.operator.scalar.StringFunctions; 
import com.facebook.presto.spi.type.StandardTypes; 
import com.facebook.presto.type.LiteralParameters; 
import com.facebook.presto.type.SqlType;  

public final class SimpleFunctions { 
   private SimpleFunctions() { 
   }  
    
   @Description("Returns summation of two numbers") 
   @ScalarFunction(“mysum") 
   //function name 
   @SqlType(StandardTypes.BIGINT) 
    
   public static long sum(@SqlType(StandardTypes.BIGINT) long num1, 
   @SqlType(StandardTypes.BIGINT) long num2) { 
      return num1 + num2; 
   } 
}

在建立應用程式之後，編譯並執行應用程式。它將生成 JAR 檔案。複製檔案並將 JAR 檔案移動到目標 Presto 伺服器外掛目錄。

編譯

mvn compile

執行

mvn package

現在，重新啟動 Presto 伺服器並連線 Presto 客戶端。然後按照下文所述執行自定函式應用程式，

$ ./presto --catalog mysql --schema default

查詢

presto:default> select mysum(10,10);

結果

 _col0  
------- 
  20