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Posted to issues-all@impala.apache.org by "Daniel Becker (Jira)" <ji...@apache.org> on 2022/11/10 16:19:00 UTC
[jira] [Created] (IMPALA-11719) Inconsistency in printing NULL values
Daniel Becker created IMPALA-11719:
--------------------------------------
Summary: Inconsistency in printing NULL values
Key: IMPALA-11719
URL: https://issues.apache.org/jira/browse/IMPALA-11719
Project: IMPALA
Issue Type: Bug
Components: Backend
Reporter: Daniel Becker
If they are top level or in collections, null values are printed as "NULL":
{code:java}
select int_array from functional_parquet.complextypestbl;
+------------------------+
| int_array |
+------------------------+
| [-1] |
| [1,2,3] |
| [NULL,1,2,NULL,3,NULL] |
| [] |
| NULL |
| NULL |
| NULL |
| NULL |
+------------------------+{code}
If they are in a struct, they are printed as "null":
{code:java}
select small_struct from functional_parquet.complextypes_structs;
+------------------------------------+
| small_struct |
+------------------------------------+
| NULL |
| {"i":19191,"s":"small_struct_str"} |
| {"i":98765,"s":null} |
| {"i":null,"s":"str"} |
| {"i":98765,"s":"abcde f"} |
| {"i":null,"s":null} |
+------------------------------------+{code}
In Hive the situation is a bit different: "NULL" is used only for top level values and "null" is printed in both collections and structs.
{code:java}
select int_array from functional_parquet.complextypestbl;
+-------------------------+
| int_array |
+-------------------------+
| [-1] |
| [1,2,3] |
| [null,1,2,null,3,null] |
| [] |
| NULL |
| NULL |
| NULL |
| NULL |
+-------------------------+{code}
{code:java}
select small_struct from functional_parquet.complextypes_structs;
+-------------------------------------+
| small_struct |
+-------------------------------------+
| NULL |
| {"i":19191,"s":"small_struct_str"} |
| {"i":98765,"s":null} |
| {"i":null,"s":"str"} |
| {"i":98765,"s":"abcde f"} |
| {"i":null,"s":null} |
+-------------------------------------+{code}
In JSON the relevant keyword is "null".
We should decide how we handle this situation.
# Have a uniform NULL representation everywhere: top level, collections and structs
** either "NULL" or "null" everywhere
# Have "NULL" on the top level and "null" in collections and structs, like Hive
# Leave everything as it is now: "NULL" at the top level and in collections, "null" in structs.
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