David Maughan created HIVE-15328: ------------------------------------ Summary: 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} -- This message was sent by Atlassian JIRA (v6.3.4#6332)