Krisztian Kasa created HIVE-24869:
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Summary: Implement Respect/Ignore Nulls in lag/lead
Key: HIVE-24869
URL: https://issues.apache.org/jira/browse/HIVE-24869
Project: Hive
Issue Type: Improvement
Components: UDF
Reporter: Krisztian Kasa
{code}
<lead or lag function> ::=
<lead or lag> <left paren> <lead or lag extent>
[ <comma> <offset> [ <comma> <default expression> ] ] <right paren>
[ <null treatment> ]
<lead or lag> ::=
LEAD | LAG
<lead or lag extent> ::=
<value expression>
<offset> ::=
<exact numeric literal>
<default expression> ::=
<value expression>
<null treatment> ::=
RESPECT NULLS | IGNORE NULLS
{code}
Example: get the a column value from the previous and the next row or return 0
if there is no previous/next row corresponding to the current row.
Respect/Ignore nulls control whether null values should be preserved or
eliminated.
{code}
SELECT
a,
LAG(a, 1, 0) OVER (ORDER BY a) IGNORE NULLS,
LEAD(a, 1, 0) OVER (ORDER BY a) RESPECT NULLS
FROM ...
{code}
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