[HIVE-24865] Implement Respect/Ignore Nulls in first/last_value

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 4.0.0-alpha-1
• Component/s: Parser, UDF
• Labels: pull-request-available
• Target Version/s: 4.0.0
• Assignee: Krisztian Kasa
• Reporter: Krisztian Kasa
• Created: 10/Mar/21 06:52
• Updated: 17/Nov/22 08:48
• Resolved: 11/Mar/21 17:41

Description

<null treatment> ::=
RESPECT NULLS | IGNORE NULLS

<first or last value function> ::=
<first or last value> <left paren> <value expression> <right paren> [ <null treatment>
]

<first or last value> ::=
FIRST_VALUE | LAST_VALUE

Example:

select last_value(b) ignore nulls over(partition by a order by b) from t1;

Existing non-standard implementation:

select last_value(b, true) over(partition by a order by b) from t1;

Issue Links

• relates to: HIVE-24908 Adding Respect/Ignore nulls as a UDAF parameter is ambiguous
• relates to: HIVE-24868 Support specifying Respect/Ignore Nulls in function parameter list
• links to: GitHub Pull Request #2056
• links to: GitHub Pull Request #2060