[jira] [Updated] (HIVE-15328) Inconsistent/incorrect handling of NULL in nested structs

["David Maughan (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-15328?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

David Maughan updated HIVE-15328:
---------------------------------
    Description: 
h2. Overview

Performing {{IS NULL}} checks against a null struct that is generated as part of a UDF correctly returns {{true}}. However, the same check against the same null struct that has been persisted to a table incorrectly returns {{false}}. Additionally, when a child field of the null struct is inspected in the same query, the result of the null check on the struct itself reverses itself to {{true}}.

The issue does not appear to be dependent on the storage format of the table as the same result is repeated with TEXTFILE, PARQUET, ORC and AVRO.

h2. Example

In this example I have used {{if(1=1, null, named_struct('c', 1))}} as a crude method of generating a simple null struct.

h4. 'b' is correctly reported as {{true}}.
{code}
hive> select
    >   b is null,
    >   b
    > from (
    >   select
    >     if(1=1, null, named_struct('c', 1)) as b
    >   ) as a;
OK
true	NULL
{code}

h4. 'b' is correctly reported as {{true}} when also inspecting 'b.c'.
{code}
hive>
    > select
    >   b is null,
    >   b.c is null,
    >   b
    > from (
    >   select
    >     if(1=1, null, named_struct('c', 1)) as b
    >   ) as a;
OK
true	true	NULL
{code}

h4. Persist the data to a table
{code}
hive>
    > create table a
    >   as
    > select
    >   if(1=1, null, named_struct('c', 1)) as b;
OK
{code}

h4. 'b' is incorrectly reported as {{false}}.
{code}
hive>
    > select
    >   b is null,
    >   b
    > from a;
OK
false	NULL
{code}

h4. 'b' is now correctly reported as {{true}} when also inspecting 'b.c'.
{code}
hive>
    > select
    >   b is null,
    >   b.c is null,
    >   b
    > from a;
OK
true	true	NULL
{code}

  was:
h2. Overview

Performing {{IS NULL}} checks against a null struct that is generated as part of a UDF correctly returns {{true}}. However, the same check against the same null struct that has been persisted to a table incorrectly returns {{false}}. Additionally, when a child field of the null struct is inspected in the same query, the result of the null check on the struct itself reverses itself to {{true}}.

The issue does not appear to be dependent on the storage format of the table as the same result is repeated with TEXTFILE, PARQUET, ORC and AVRO.

h2. Example

In this example I have used {{if(1=1, null, named_struct('c', 1)}} as a crude method of generating a simple null struct.

h4. 'b' is correctly reported as {{true}}.
{code}
hive> select
    >   b is null,
    >   b
    > from (
    >   select
    >     if(1=1, null, named_struct('c', 1)) as b
    >   ) as a;
OK
true	NULL
{code}

h4. 'b' is correctly reported as {{true}} when also inspecting 'b.c'.
{code}
hive>
    > select
    >   b is null,
    >   b.c is null,
    >   b
    > from (
    >   select
    >     if(1=1, null, named_struct('c', 1)) as b
    >   ) as a;
OK
true	true	NULL
{code}

h4. Persist the data to a table
{code}
hive>
    > create table a
    >   as
    > select
    >   if(1=1, null, named_struct('c', 1)) as b;
OK
{code}

h4. 'b' is incorrectly reported as {{false}}.
{code}
hive>
    > select
    >   b is null,
    >   b
    > from a;
OK
false	NULL
{code}

h4. 'b' is now correctly reported as {{true}} when also inspecting 'b.c'.
{code}
hive>
    > select
    >   b is null,
    >   b.c is null,
    >   b
    > from a;
OK
true	true	NULL
{code}


> Inconsistent/incorrect handling of NULL in nested structs
> ---------------------------------------------------------
>
>                 Key: HIVE-15328
>                 URL: https://issues.apache.org/jira/browse/HIVE-15328
>             Project: Hive
>          Issue Type: Bug
>          Components: Hive
>    Affects Versions: 2.1.0
>            Reporter: David Maughan
>
> h2. Overview
> Performing {{IS NULL}} checks against a null struct that is generated as part of a UDF correctly returns {{true}}. However, the same check against the same null struct that has been persisted to a table incorrectly returns {{false}}. Additionally, when a child field of the null struct is inspected in the same query, the result of the null check on the struct itself reverses itself to {{true}}.
> The issue does not appear to be dependent on the storage format of the table as the same result is repeated with TEXTFILE, PARQUET, ORC and AVRO.
> h2. Example
> In this example I have used {{if(1=1, null, named_struct('c', 1))}} as a crude method of generating a simple null struct.
> h4. 'b' is correctly reported as {{true}}.
> {code}
> hive> select
>     >   b is null,
>     >   b
>     > from (
>     >   select
>     >     if(1=1, null, named_struct('c', 1)) as b
>     >   ) as a;
> OK
> true	NULL
> {code}
> h4. 'b' is correctly reported as {{true}} when also inspecting 'b.c'.
> {code}
> hive>
>     > select
>     >   b is null,
>     >   b.c is null,
>     >   b
>     > from (
>     >   select
>     >     if(1=1, null, named_struct('c', 1)) as b
>     >   ) as a;
> OK
> true	true	NULL
> {code}
> h4. Persist the data to a table
> {code}
> hive>
>     > create table a
>     >   as
>     > select
>     >   if(1=1, null, named_struct('c', 1)) as b;
> OK
> {code}
> h4. 'b' is incorrectly reported as {{false}}.
> {code}
> hive>
>     > select
>     >   b is null,
>     >   b
>     > from a;
> OK
> false	NULL
> {code}
> h4. 'b' is now correctly reported as {{true}} when also inspecting 'b.c'.
> {code}
> hive>
>     > select
>     >   b is null,
>     >   b.c is null,
>     >   b
>     > from a;
> OK
> true	true	NULL
> {code}



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