My travels in the hive type is an array of hive

CodePudding user response:

Of course ~ I see you have a written udf. You pass an array & lt; int> How to read the newspaper in the wrong hint is introduced into struct type?

CodePudding user response:

In give you a demo. Used to get data in one of the biggest value

 
Package cn.com.diditaxi.hive.cf; 

Import org, apache hadoop. Hive. Ql. Exec. The Description; 
Import org, apache hadoop. Hive. Ql. Exec. UDFArgumentException; 
Import org, apache hadoop. Hive. Ql. Exec. UDFArgumentTypeException; 
Import org, apache hadoop. Hive. Ql. Metadata. HiveException; 
Import org, apache hadoop. Hive. Ql. Udf. Generic. GenericUDF; 
Import org, apache hadoop. Hive. Ql. Udf. Generic. GenericUDFUtils; 
Import org, apache hadoop. Hive. Serde2. Objectinspector. Objectinspector; 
Import org, apache hadoop. Hive. Serde2. Objectinspector. ObjectInspectorUtils; 
The import org. Apache. Hive. PDK. HivePdkUnitTest; 
The import org. Apache. Hive. PDK. HivePdkUnitTests; 

/* * 
* GenericUDF Class for SQL construct "greatest (value1, value2, value3,... ). "
* Oracle 's CREATEST returns the greatest of the list of one or more expressions. 
* 
*/
@ the Description (name="greatest" value="HTTP://https://bbs.csdn.net/topics/_FUNC_ (value1, value2, value3,... ) + "
"- Returns the greatest value in the list.", 
Extended="Example: \ n" + "& gt; The SELECT _FUNC_ (2, 5, 12, 3) the FROM SRC; 12 "\ n) 
@ HivePdkUnitTests (setup="create table dual_data (int I); "
+ "insert the overwrite table dual_data select 1 from dual limit 1;" , 
The cleanup="drop table if the exists dual_data;" , 
Cases in={
@ HivePdkUnitTest (query="SELECT nexr_greatest (2, 5, 12, 3)" + 
"FROM dual_data;" , the result="12"), 
@ HivePdkUnitTest (query="SELECT nexr_greatest (' 2 ', '5', '12', '3')" + 
"FROM dual_data;" , the result="5"), 
@ HivePdkUnitTest (query="SELECT nexr_greatest (apples, oranges, 'bannanas)" + 
"FROM dual_data;" , the result="oranges")}) 
Public class GenericUDFGreatest extends GenericUDF {

Private ObjectInspector [] argumentOIs; 
Private GenericUDFUtils. ReturnObjectInspectorResolver returnOIResolver; 

@ Override 
Public ObjectInspector initialize (ObjectInspector [] the arguments) throws UDFArgumentException {

for (int i=0; i If (the arguments [I] getCategory ()!=ObjectInspector. Category. PRIMITIVE) {
Throw new UDFArgumentTypeException (I, "Only primitive type, the arguments are accepted but" 
+ the arguments [I] getTypeName () + "is passed."); 
} 
} 

ArgumentOIs=the arguments; 
ReturnOIResolver=new GenericUDFUtils. ReturnObjectInspectorResolver (true); 
for (int i=0; i if (! ReturnOIResolver. Update (the arguments [I]) {
Throw new UDFArgumentTypeException (I, "The value of The return should have The same type: " "
+ returnOIResolver. The get (). GetTypeName () + 
"" is expected but \ "" + the arguments [I] getTypeName () 
+ "" is found "); 
} 
} 

Return returnOIResolver. The get (); 
} 

@ Override 
Public Object the evaluate (DeferredObject [] fields) throws HiveException {
The Object greatestObject=null; 
ObjectInspector greatestOI=null; 

for (int i=0; i Object fieldObject=fields [I] the get (); 
If (greatestObject==null) {
GreatestObject=fieldObject; 
GreatestOI=argumentOIs [I]; 
continue; 
} 

If (ObjectInspectorUtils.com pare said (greatestObject greatestOI, fieldObject, argumentOIs [I]) & lt;=0) {
GreatestObject=fieldObject; 
GreatestOI=argumentOIs [I]; 
} 
} 

Return returnOIResolver. ConvertIfNecessary (greatestObject greatestOI); 
} 

@ Override 
Public String getDisplayString (String [] children) {
StringBuilder sb=new StringBuilder(); 
Sb. Append (greatest (" "); 
for (int i=0; i Sb. Append (children [I]), append (", "); 
} 
Sb. Append (children [children] length - 1), append (") "); 
return sb.toString(); 
} 

}