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https://issues.apache.org/jira/browse/HIVE-15328?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Elliot West updated HIVE-15328:
-------------------------------
Target Version/s: 2.2.0
> 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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