Krisztian Kasa created HIVE-24908:
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Summary: Adding Respect/Ignore nulls as a UDAF parameter is
ambiguous
Key: HIVE-24908
URL: https://issues.apache.org/jira/browse/HIVE-24908
Project: Hive
Issue Type: Bug
Components: UDF
Reporter: Krisztian Kasa
Assignee: Krisztian Kasa
Both function calls translated to the same UDAF call:
{code}
SELECT lead(a, 2, true) ...
SELECT lead(a, 2) IGNORE NULLS ...
{code}
IGNORE NULLS is passed as an extra constant boolean parameter to the UDAF
https://github.com/apache/hive/blob/eed78dfdcb6dfc2de400397a60de12e6f62b96e2/ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/translator/ASTConverter.java#L743
However the semantics of the two function calls has different semantics:
* *lead(a, 2, true)* - 'true' is the default value: "The value of DEFAULT is
returned as the result if there is no row corresponding to the OFFSET number of
rows before R within P (for the lag function) or after R within P (for the lead
function)"
* *lead(a, 2) IGNORE NULLS* - For each row in the current window find the 2nd
not-NULL value starting directly after the current row.
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