[
https://issues.apache.org/jira/browse/HIVE-24865?focusedWorklogId=563531&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-563531
]
ASF GitHub Bot logged work on HIVE-24865:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 10/Mar/21 07:31
Start Date: 10/Mar/21 07:31
Worklog Time Spent: 10m
Work Description: kasakrisz opened a new pull request #2056:
URL: https://github.com/apache/hive/pull/2056
### What changes were proposed in this pull request?
1. Introduce `RESPECT NULLS` `IGNORE NULLS` syntax and map it to boolean
values.
2. Treat this value as a boolean parameter of the specified window function.
3. `first/last_value` functions already supports this extra parameter.
### Why are the changes needed?
Support specifying ignore nulls in a standard way.
### Does this PR introduce _any_ user-facing change?
Yes, but existing behavior not changed. Ignore nulls can be specified two
ways:
```
Standard: select last_value(b) ignore nulls over
Legacy: select last_value(b, true) over
```
### How was this patch tested?
```
mvn test -Dtest.output.overwrite -DskipSparkTests
-Dtest=TestMiniLlapLocalCliDriver -Dqfile=windowing_navfn.q -pl itests/qtest
-Pitests
```
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Issue Time Tracking
-------------------
Worklog Id: (was: 563531)
Remaining Estimate: 0h
Time Spent: 10m
> Implement Respect/Ignore Nulls in first/last_value
> --------------------------------------------------
>
> Key: HIVE-24865
> URL: https://issues.apache.org/jira/browse/HIVE-24865
> Project: Hive
> Issue Type: New Feature
> Components: Parser, UDF
> Reporter: Krisztian Kasa
> Assignee: Krisztian Kasa
> Priority: Minor
> Time Spent: 10m
> Remaining Estimate: 0h
>
> {code:java}
> <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
> {code}
> Example:
> {code:java}
> select last_value(b) ignore nulls over(partition by a order by b) from t1;
> {code}
> Existing non-standard implementation:
> {code:java}
> select last_value(b, true) over(partition by a order by b) from t1;
> {code}
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