HIVE-28825: Support conversion of complex types to String

ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFToString.java

@@ -21,22 +21,17 @@
 import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
 import org.apache.hadoop.hive.ql.metadata.HiveException;
 import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
-import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;
-import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorConverter.TextConverter;
+import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorConverters;
 import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 @Description(name = "string",
 value = "CAST(<value> as STRING) - Converts the argument to a string value.",
 extended = "Example:\n "
 + "  > SELECT CAST(1234 AS string) FROM src LIMIT 1;\n"
 + "  '1234'")
 public class GenericUDFToString extends GenericUDF {
-  private static final Logger LOG = LoggerFactory.getLogger(GenericUDFToString.class.getName());
 
-  private transient PrimitiveObjectInspector argumentOI;
-  private transient TextConverter converter;
+  private transient ObjectInspectorConverters.Converter converter;
 
   public GenericUDFToString() {
   }
@@ -46,14 +41,9 @@ public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumen
     if (arguments.length != 1) {
       throw new UDFArgumentException("STRING cast requires a value argument");
     }
-    try {
-      argumentOI = (PrimitiveObjectInspector) arguments[0];
-    } catch (ClassCastException e) {
-      throw new UDFArgumentException(
-          "The function STRING takes only primitive types");
-    }
 
-    converter = new TextConverter(argumentOI);
+    converter = ObjectInspectorConverters
+        .getConverter(arguments[0], PrimitiveObjectInspectorFactory.writableStringObjectInspector);
     return PrimitiveObjectInspectorFactory.writableStringObjectInspector;
   }
 

ql/src/test/queries/clientpositive/udf_to_string.q

@@ -1,21 +1,34 @@
---! qt:dataset:src
+--! qt:dataset:alltypesorc
 set hive.fetch.task.conversion=more;
 
 -- Conversion of main primitive types to String type:
-SELECT CAST(NULL AS STRING) FROM src tablesample (1 rows);
+SELECT CAST(NULL AS STRING);
 
-SELECT CAST(TRUE AS STRING) FROM src tablesample (1 rows);
+SELECT CAST(TRUE AS STRING);
 
-SELECT CAST(CAST(1 AS TINYINT) AS STRING) FROM src tablesample (1 rows);
-SELECT CAST(CAST(-18 AS SMALLINT) AS STRING) FROM src tablesample (1 rows);
-SELECT CAST(-129 AS STRING) FROM src tablesample (1 rows);
-SELECT CAST(CAST(-1025 AS BIGINT) AS STRING) FROM src tablesample (1 rows);
+SELECT CAST(CAST(1 AS TINYINT) AS STRING);
+SELECT CAST(CAST(-18 AS SMALLINT) AS STRING);
+SELECT CAST(-129 AS STRING);
+SELECT CAST(CAST(-1025 AS BIGINT) AS STRING);
 
-SELECT CAST(CAST(-3.14 AS DOUBLE) AS STRING) FROM src tablesample (1 rows);
-SELECT CAST(CAST(-3.14 AS FLOAT) AS STRING) FROM src tablesample (1 rows);
-SELECT CAST(CAST(-3.14 AS DECIMAL(3,2)) AS STRING) FROM src tablesample (1 rows);
+SELECT CAST(CAST(-3.14 AS DOUBLE) AS STRING);
+SELECT CAST(CAST(-3.14 AS FLOAT) AS STRING);
+SELECT CAST(CAST(-3.14 AS DECIMAL(3,2)) AS STRING);
 
-SELECT CAST('Foo' AS STRING) FROM src tablesample (1 rows);
+SELECT CAST('Foo' AS STRING);
 
 SELECT CAST(from_utc_timestamp(timestamp '2018-05-02 15:30:30', 'PST') - from_utc_timestamp(timestamp '1970-01-30 16:00:00', 'PST') AS STRING);
 SELECT CAST(interval_year_month('1-2') AS STRING);
+
+-- Conversion of complex types to String type:
+select '"' || cast(array(*) as string) || '"' from alltypesorc limit 3;
+select '"' || cast(struct(*) as string) || '"' from alltypesorc limit 3;
+select '"' || cast(map("ctinyint" , ctinyint, "csmallint" , csmallint, "cint" , cint, "cbigint" , cbigint, "cfloat" , cfloat, "cdouble" , cdouble, "cstring1" , cstring1, "cstring2" , cstring2, "ctimestamp1" , ctimestamp1, "ctimestamp2" , ctimestamp2, "cboolean1" , cboolean1, "cboolean2" , cboolean2) as string) || '"' from alltypesorc limit 3;
+select '"' || cast(create_union(if(csmallint % 2 == 0, 0, 1), array(*), struct(*)) as string) || '"' from alltypesorc limit 3;
+
+select '"' || cast(
+        struct(
+            map("key1", array(csmallint, csmallint+1), "key2", array(csmallint+2, csmallint+3)),
+            struct(cstring1, cboolean1, create_union(if(csmallint % 2 == 0, 0, 1), array(*), struct(*)))
+        )
+    as string) || '"' from alltypesorc limit 3;

ql/src/test/results/clientpositive/llap/udf_to_string.q.out

@@ -1,91 +1,91 @@
-PREHOOK: query: SELECT CAST(NULL AS STRING) FROM src tablesample (1 rows)
+PREHOOK: query: SELECT CAST(NULL AS STRING)
 PREHOOK: type: QUERY
-PREHOOK: Input: default@src
+PREHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
-POSTHOOK: query: SELECT CAST(NULL AS STRING) FROM src tablesample (1 rows)
+POSTHOOK: query: SELECT CAST(NULL AS STRING)
 POSTHOOK: type: QUERY
-POSTHOOK: Input: default@src
+POSTHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
 NULL
-PREHOOK: query: SELECT CAST(TRUE AS STRING) FROM src tablesample (1 rows)
+PREHOOK: query: SELECT CAST(TRUE AS STRING)
 PREHOOK: type: QUERY
-PREHOOK: Input: default@src
+PREHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
-POSTHOOK: query: SELECT CAST(TRUE AS STRING) FROM src tablesample (1 rows)
+POSTHOOK: query: SELECT CAST(TRUE AS STRING)
 POSTHOOK: type: QUERY
-POSTHOOK: Input: default@src
+POSTHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
 TRUE
-PREHOOK: query: SELECT CAST(CAST(1 AS TINYINT) AS STRING) FROM src tablesample (1 rows)
+PREHOOK: query: SELECT CAST(CAST(1 AS TINYINT) AS STRING)
 PREHOOK: type: QUERY
-PREHOOK: Input: default@src
+PREHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
-POSTHOOK: query: SELECT CAST(CAST(1 AS TINYINT) AS STRING) FROM src tablesample (1 rows)
+POSTHOOK: query: SELECT CAST(CAST(1 AS TINYINT) AS STRING)
 POSTHOOK: type: QUERY
-POSTHOOK: Input: default@src
+POSTHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
 1
-PREHOOK: query: SELECT CAST(CAST(-18 AS SMALLINT) AS STRING) FROM src tablesample (1 rows)
+PREHOOK: query: SELECT CAST(CAST(-18 AS SMALLINT) AS STRING)
 PREHOOK: type: QUERY
-PREHOOK: Input: default@src
+PREHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
-POSTHOOK: query: SELECT CAST(CAST(-18 AS SMALLINT) AS STRING) FROM src tablesample (1 rows)
+POSTHOOK: query: SELECT CAST(CAST(-18 AS SMALLINT) AS STRING)
 POSTHOOK: type: QUERY
-POSTHOOK: Input: default@src
+POSTHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
 -18
-PREHOOK: query: SELECT CAST(-129 AS STRING) FROM src tablesample (1 rows)
+PREHOOK: query: SELECT CAST(-129 AS STRING)
 PREHOOK: type: QUERY
-PREHOOK: Input: default@src
+PREHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
-POSTHOOK: query: SELECT CAST(-129 AS STRING) FROM src tablesample (1 rows)
+POSTHOOK: query: SELECT CAST(-129 AS STRING)
 POSTHOOK: type: QUERY
-POSTHOOK: Input: default@src
+POSTHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
 -129
-PREHOOK: query: SELECT CAST(CAST(-1025 AS BIGINT) AS STRING) FROM src tablesample (1 rows)
+PREHOOK: query: SELECT CAST(CAST(-1025 AS BIGINT) AS STRING)
 PREHOOK: type: QUERY
-PREHOOK: Input: default@src
+PREHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
-POSTHOOK: query: SELECT CAST(CAST(-1025 AS BIGINT) AS STRING) FROM src tablesample (1 rows)
+POSTHOOK: query: SELECT CAST(CAST(-1025 AS BIGINT) AS STRING)
 POSTHOOK: type: QUERY
-POSTHOOK: Input: default@src
+POSTHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
 -1025
-PREHOOK: query: SELECT CAST(CAST(-3.14 AS DOUBLE) AS STRING) FROM src tablesample (1 rows)
+PREHOOK: query: SELECT CAST(CAST(-3.14 AS DOUBLE) AS STRING)
 PREHOOK: type: QUERY
-PREHOOK: Input: default@src
+PREHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
-POSTHOOK: query: SELECT CAST(CAST(-3.14 AS DOUBLE) AS STRING) FROM src tablesample (1 rows)
+POSTHOOK: query: SELECT CAST(CAST(-3.14 AS DOUBLE) AS STRING)
 POSTHOOK: type: QUERY
-POSTHOOK: Input: default@src
+POSTHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
 -3.14
-PREHOOK: query: SELECT CAST(CAST(-3.14 AS FLOAT) AS STRING) FROM src tablesample (1 rows)
+PREHOOK: query: SELECT CAST(CAST(-3.14 AS FLOAT) AS STRING)
 PREHOOK: type: QUERY
-PREHOOK: Input: default@src
+PREHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
-POSTHOOK: query: SELECT CAST(CAST(-3.14 AS FLOAT) AS STRING) FROM src tablesample (1 rows)
+POSTHOOK: query: SELECT CAST(CAST(-3.14 AS FLOAT) AS STRING)
 POSTHOOK: type: QUERY
-POSTHOOK: Input: default@src
+POSTHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
 -3.14
-PREHOOK: query: SELECT CAST(CAST(-3.14 AS DECIMAL(3,2)) AS STRING) FROM src tablesample (1 rows)
+PREHOOK: query: SELECT CAST(CAST(-3.14 AS DECIMAL(3,2)) AS STRING)
 PREHOOK: type: QUERY
-PREHOOK: Input: default@src
+PREHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
-POSTHOOK: query: SELECT CAST(CAST(-3.14 AS DECIMAL(3,2)) AS STRING) FROM src tablesample (1 rows)
+POSTHOOK: query: SELECT CAST(CAST(-3.14 AS DECIMAL(3,2)) AS STRING)
 POSTHOOK: type: QUERY
-POSTHOOK: Input: default@src
+POSTHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
 -3.14
-PREHOOK: query: SELECT CAST('Foo' AS STRING) FROM src tablesample (1 rows)
+PREHOOK: query: SELECT CAST('Foo' AS STRING)
 PREHOOK: type: QUERY
-PREHOOK: Input: default@src
+PREHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
-POSTHOOK: query: SELECT CAST('Foo' AS STRING) FROM src tablesample (1 rows)
+POSTHOOK: query: SELECT CAST('Foo' AS STRING)
 POSTHOOK: type: QUERY
-POSTHOOK: Input: default@src
+POSTHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
 Foo
 PREHOOK: query: SELECT CAST(from_utc_timestamp(timestamp '2018-05-02 15:30:30', 'PST') - from_utc_timestamp(timestamp '1970-01-30 16:00:00', 'PST') AS STRING)
@@ -106,3 +106,68 @@ POSTHOOK: type: QUERY
 POSTHOOK: Input: _dummy_database@_dummy_table
 #### A masked pattern was here ####
 1-2
+PREHOOK: query: select '"' || cast(array(*) as string) || '"' from alltypesorc limit 3
+PREHOOK: type: QUERY
+PREHOOK: Input: default@alltypesorc
+#### A masked pattern was here ####
+POSTHOOK: query: select '"' || cast(array(*) as string) || '"' from alltypesorc limit 3
+POSTHOOK: type: QUERY
+POSTHOOK: Input: default@alltypesorc
+#### A masked pattern was here ####
+"["-50","-13326","528534767",null,"-50.0","-13326.0","cvLH6Eat2yFsyy7p",null,"1969-12-31 15:59:46.674","1969-12-31 16:00:08.875","TRUE",null]"
+"[null,"-4213","528534767",null,null,"-4213.0","cvLH6Eat2yFsyy7p",null,null,"1969-12-31 16:00:13.589","TRUE",null]"
+"["-28","-15813","528534767",null,"-28.0","-15813.0","cvLH6Eat2yFsyy7p",null,"1969-12-31 15:59:55.787","1969-12-31 16:00:01.546","TRUE",null]"
+PREHOOK: query: select '"' || cast(struct(*) as string) || '"' from alltypesorc limit 3
+PREHOOK: type: QUERY
+PREHOOK: Input: default@alltypesorc
+#### A masked pattern was here ####
+POSTHOOK: query: select '"' || cast(struct(*) as string) || '"' from alltypesorc limit 3
+POSTHOOK: type: QUERY
+POSTHOOK: Input: default@alltypesorc
+#### A masked pattern was here ####
+"{"col1":-50,"col2":-13326,"col3":528534767,"col4":null,"col5":-50.0,"col6":-13326.0,"col7":"cvLH6Eat2yFsyy7p","col8":null,"col9":"1969-12-31 15:59:46.674","col10":"1969-12-31 16:00:08.875","col11":true,"col12":null}"
+"{"col1":null,"col2":-4213,"col3":528534767,"col4":null,"col5":null,"col6":-4213.0,"col7":"cvLH6Eat2yFsyy7p","col8":null,"col9":null,"col10":"1969-12-31 16:00:13.589","col11":true,"col12":null}"
+"{"col1":-28,"col2":-15813,"col3":528534767,"col4":null,"col5":-28.0,"col6":-15813.0,"col7":"cvLH6Eat2yFsyy7p","col8":null,"col9":"1969-12-31 15:59:55.787","col10":"1969-12-31 16:00:01.546","col11":true,"col12":null}"
+PREHOOK: query: select '"' || cast(map("ctinyint" , ctinyint, "csmallint" , csmallint, "cint" , cint, "cbigint" , cbigint, "cfloat" , cfloat, "cdouble" , cdouble, "cstring1" , cstring1, "cstring2" , cstring2, "ctimestamp1" , ctimestamp1, "ctimestamp2" , ctimestamp2, "cboolean1" , cboolean1, "cboolean2" , cboolean2) as string) || '"' from alltypesorc limit 3
+PREHOOK: type: QUERY
+PREHOOK: Input: default@alltypesorc
+#### A masked pattern was here ####
+POSTHOOK: query: select '"' || cast(map("ctinyint" , ctinyint, "csmallint" , csmallint, "cint" , cint, "cbigint" , cbigint, "cfloat" , cfloat, "cdouble" , cdouble, "cstring1" , cstring1, "cstring2" , cstring2, "ctimestamp1" , ctimestamp1, "ctimestamp2" , ctimestamp2, "cboolean1" , cboolean1, "cboolean2" , cboolean2) as string) || '"' from alltypesorc limit 3
+POSTHOOK: type: QUERY
+POSTHOOK: Input: default@alltypesorc
+#### A masked pattern was here ####
+"{"ctinyint":"-50","csmallint":"-13326","cint":"528534767","cbigint":null,"cfloat":"-50.0","cdouble":"-13326.0","cstring1":"cvLH6Eat2yFsyy7p","cstring2":null,"ctimestamp1":"1969-12-31 15:59:46.674","ctimestamp2":"1969-12-31 16:00:08.875","cboolean1":"TRUE","cboolean2":null}"
+"{"ctinyint":null,"csmallint":"-4213","cint":"528534767","cbigint":null,"cfloat":null,"cdouble":"-4213.0","cstring1":"cvLH6Eat2yFsyy7p","cstring2":null,"ctimestamp1":null,"ctimestamp2":"1969-12-31 16:00:13.589","cboolean1":"TRUE","cboolean2":null}"
+"{"ctinyint":"-28","csmallint":"-15813","cint":"528534767","cbigint":null,"cfloat":"-28.0","cdouble":"-15813.0","cstring1":"cvLH6Eat2yFsyy7p","cstring2":null,"ctimestamp1":"1969-12-31 15:59:55.787","ctimestamp2":"1969-12-31 16:00:01.546","cboolean1":"TRUE","cboolean2":null}"
+PREHOOK: query: select '"' || cast(create_union(if(csmallint % 2 == 0, 0, 1), array(*), struct(*)) as string) || '"' from alltypesorc limit 3
+PREHOOK: type: QUERY
+PREHOOK: Input: default@alltypesorc
+#### A masked pattern was here ####
+POSTHOOK: query: select '"' || cast(create_union(if(csmallint % 2 == 0, 0, 1), array(*), struct(*)) as string) || '"' from alltypesorc limit 3
+POSTHOOK: type: QUERY
+POSTHOOK: Input: default@alltypesorc
+#### A masked pattern was here ####
+"{0:["-50","-13326","528534767",null,"-50.0","-13326.0","cvLH6Eat2yFsyy7p",null,"1969-12-31 15:59:46.674","1969-12-31 16:00:08.875","TRUE",null]}"
+"{1:{"col1":null,"col2":-4213,"col3":528534767,"col4":null,"col5":null,"col6":-4213.0,"col7":"cvLH6Eat2yFsyy7p","col8":null,"col9":null,"col10":"1969-12-31 16:00:13.589","col11":true,"col12":null}}"
+"{1:{"col1":-28,"col2":-15813,"col3":528534767,"col4":null,"col5":-28.0,"col6":-15813.0,"col7":"cvLH6Eat2yFsyy7p","col8":null,"col9":"1969-12-31 15:59:55.787","col10":"1969-12-31 16:00:01.546","col11":true,"col12":null}}"
+PREHOOK: query: select '"' || cast(
+        struct(
+            map("key1", array(csmallint, csmallint+1), "key2", array(csmallint+2, csmallint+3)),
+            struct(cstring1, cboolean1, create_union(if(csmallint % 2 == 0, 0, 1), array(*), struct(*)))
+        )
+    as string) || '"' from alltypesorc limit 3
+PREHOOK: type: QUERY
+PREHOOK: Input: default@alltypesorc
+#### A masked pattern was here ####
+POSTHOOK: query: select '"' || cast(
+        struct(
+            map("key1", array(csmallint, csmallint+1), "key2", array(csmallint+2, csmallint+3)),
+            struct(cstring1, cboolean1, create_union(if(csmallint % 2 == 0, 0, 1), array(*), struct(*)))
+        )
+    as string) || '"' from alltypesorc limit 3
+POSTHOOK: type: QUERY
+POSTHOOK: Input: default@alltypesorc
+#### A masked pattern was here ####
+"{"col1":{"key1":[-13326,-13325],"key2":[-13324,-13323]},"col2":{"col1":"cvLH6Eat2yFsyy7p","col2":true,"col3":{0:["-50","-13326","528534767",null,"-50.0","-13326.0","cvLH6Eat2yFsyy7p",null,"1969-12-31 15:59:46.674","1969-12-31 16:00:08.875","TRUE",null]}}}"
+"{"col1":{"key1":[-4213,-4212],"key2":[-4211,-4210]},"col2":{"col1":"cvLH6Eat2yFsyy7p","col2":true,"col3":{1:{"col1":null,"col2":-4213,"col3":528534767,"col4":null,"col5":null,"col6":-4213.0,"col7":"cvLH6Eat2yFsyy7p","col8":null,"col9":null,"col10":"1969-12-31 16:00:13.589","col11":true,"col12":null}}}}"
+"{"col1":{"key1":[-15813,-15812],"key2":[-15811,-15810]},"col2":{"col1":"cvLH6Eat2yFsyy7p","col2":true,"col3":{1:{"col1":-28,"col2":-15813,"col3":528534767,"col4":null,"col5":-28.0,"col6":-15813.0,"col7":"cvLH6Eat2yFsyy7p","col8":null,"col9":"1969-12-31 15:59:55.787","col10":"1969-12-31 16:00:01.546","col11":true,"col12":null}}}}"

serde/src/java/org/apache/hadoop/hive/serde2/objectinspector/ObjectInspectorConverters.java

@@ -24,6 +24,7 @@
 
 import org.apache.hadoop.hive.common.classification.InterfaceAudience;
 import org.apache.hadoop.hive.common.classification.InterfaceStability;
+import org.apache.hadoop.hive.serde2.SerDeUtils;
 import org.apache.hadoop.hive.serde2.objectinspector.primitive.JavaStringObjectInspector;
 import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorConverter;
 import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
@@ -45,7 +46,7 @@
 import org.apache.hadoop.hive.serde2.objectinspector.primitive.SettableTimestampLocalTZObjectInspector;
 import org.apache.hadoop.hive.serde2.objectinspector.primitive.VoidObjectInspector;
 import org.apache.hadoop.hive.serde2.objectinspector.primitive.WritableStringObjectInspector;
-import org.apache.hadoop.hive.serde2.typeinfo.PrimitiveTypeInfo;
+import org.apache.hadoop.io.Text;
 
 /**
  * ObjectInspectorConverters.
@@ -175,7 +176,7 @@ public static Converter getConverter(ObjectInspector inputOI,
     }
     switch (outputOI.getCategory()) {
     case PRIMITIVE:
-      return getConverter((PrimitiveObjectInspector) inputOI, (PrimitiveObjectInspector) outputOI);
+      return getConverterForPrimitiveOutput(inputOI, (PrimitiveObjectInspector) outputOI);
     case STRUCT:
       return new StructConverter(inputOI,
           (SettableStructObjectInspector) outputOI);
@@ -194,6 +195,23 @@ public static Converter getConverter(ObjectInspector inputOI,
           + " not supported yet.");
     }
   }
+
+  private static Converter getConverterForPrimitiveOutput(ObjectInspector inputOI, 
+                                                          PrimitiveObjectInspector outputOI) {
+    switch (inputOI.getCategory()) {
+      case PRIMITIVE:
+        return getConverter((PrimitiveObjectInspector) inputOI, outputOI);
+      case STRUCT:
+      case LIST:
+      case MAP:
+      case UNION:
+        return new TextConverterForComplexTypes(inputOI);
+      default:
+        throw new RuntimeException("Hive internal error: conversion of "
+            + inputOI.getTypeName() + " to " + outputOI.getTypeName()
+            + " not supported yet.");
+    }
+  }
 
   /*
    * getConvertedOI with caching to store settable properties of the object
@@ -575,5 +593,18 @@ public Object convert(Object input) {
   private ObjectInspectorConverters() {
     // prevent instantiation
   }
+
+  public static class TextConverterForComplexTypes implements Converter {
+
+    private final ObjectInspector inputOI;
 
+    public TextConverterForComplexTypes(ObjectInspector inputOI) {
+      this.inputOI = inputOI;
+    }
+
+    @Override
+    public Object convert(Object input) {
+      return new Text(SerDeUtils.getJSONString(input, inputOI));
+    }
+  }
 }