Sam Tunnicliffe created HIVE-6337:
-------------------------------------

             Summary: Allow non-primitive types to be converted to other types
                 Key: HIVE-6337
                 URL: https://issues.apache.org/jira/browse/HIVE-6337
             Project: Hive
          Issue Type: Improvement
            Reporter: Sam Tunnicliffe


The use case I have in mind is to write a UDF which allows collections of one 
type to be converted to collections of another type. For instance, I'd like to 
be able to define a UDF (string_to_int) to do:

{code}
INSERT INTO TABLE int_table SELECT cast(id_string as int), 
string_to_int(strings) FROM string_table;
{code}

where the tables are defined like so:

{code}
hive> DESCRIBE string_table;
OK
id_string               string                  None                
strings                 array<string>           None 
hive> DESCRIBE int_table;
OK
id_int                  int                     None                
ints                    array<int>              None 
{code}

Right now, this fails at the analysis stage with:

{code}
2014-01-30 12:01:13,300 ERROR ql.Driver (SessionState.java:printError(419)) - 
FAILED: SemanticException [Error 10044]: Line 1:18 Cannot insert into target 
table because column number/types are different 'int_table': Cannot convert 
column 1 from array<string> to array<int>.
org.apache.hadoop.hive.ql.parse.SemanticException: Line 1:18 Cannot insert into 
target table because column number/types are different 'int_table': Cannot 
convert column 1 from array<string> to array<int>.
        at 
org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.genConversionSelectOperator(SemanticAnalyzer.java:5403)
        at 
org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.genFileSinkPlan(SemanticAnalyzer.java:5240)
        at 
org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.genPostGroupByBodyPlan(SemanticAnalyzer.java:7428)
        at 
org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.genBodyPlan(SemanticAnalyzer.java:7320)
        at 
org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.genPlan(SemanticAnalyzer.java:8123)
        at 
org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.analyzeInternal(SemanticAnalyzer.java:8349)
        at 
org.apache.hadoop.hive.ql.parse.BaseSemanticAnalyzer.analyze(BaseSemanticAnalyzer.java:284)
        at org.apache.hadoop.hive.ql.Driver.compile(Driver.java:441)
        at org.apache.hadoop.hive.ql.Driver.compile(Driver.java:342)
        at org.apache.hadoop.hive.ql.Driver.runInternal(Driver.java:977)
        at org.apache.hadoop.hive.ql.Driver.run(Driver.java:888)
        at 
org.apache.hadoop.hive.cli.CliDriver.processLocalCmd(CliDriver.java:259)
        at org.apache.hadoop.hive.cli.CliDriver.processCmd(CliDriver.java:216)
        at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:413)
        at 
org.apache.hadoop.hive.cli.CliDriver.executeDriver(CliDriver.java:781)
        at org.apache.hadoop.hive.cli.CliDriver.run(CliDriver.java:675)
        at org.apache.hadoop.hive.cli.CliDriver.main(CliDriver.java:614)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at 
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.apache.hadoop.util.RunJar.main(RunJar.java:156)
{code}



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