[jira] [Created] (HIVE-30136) Vectorized LEAD/LAG uses wrong constant for DOUBLE/DECIMAL literal default (reads long 0)

[Hemanth Umashankar (Jira)]

Hemanth Umashankar created HIVE-30136:
-----------------------------------------

             Summary: Vectorized LEAD/LAG uses wrong constant for 
DOUBLE/DECIMAL literal default (reads long 0)
                 Key: HIVE-30136
                 URL: https://issues.apache.org/jira/browse/HIVE-30136
             Project: Hive
          Issue Type: Bug
            Reporter: Hemanth Umashankar


With vectorization enabled, LAG/LEAD(..., ..., <double literal>) returns 0.0 on 
rows that need the default (e.g. first row per partition for LAG offset 1). 
With vectorization disabled, the same query returns the correct default.

Suspected cause: VectorPTFEvaluatorAbstractLeadLag.initDefaultValue() always 
uses ConstantVectorExpression.getLongValue(); double literals use doubleValue, 
so longValue is 0.

Repro:

CREATE TABLE lag_default_repro (
  region   STRING,
  sale_id  INT,
  amount   DOUBLE
);

INSERT INTO lag_default_repro VALUES
  ('east', 1, 10.0),
  ('east', 2, 20.0),
  ('west', 1, 100.0);

SET hive.vectorized.execution.enabled=false;
SELECT
  region,
  sale_id,
  amount,
  LAG(amount, 1, 2.5) OVER (PARTITION BY region ORDER BY sale_id) AS 
prev_amount_or_default
FROM lag_default_repro
ORDER BY region, sale_id;

SET hive.vectorized.execution.enabled=true;
SELECT
  region,
  sale_id,
  amount,
  LAG(amount, 1, 2.5) OVER (PARTITION BY region ORDER BY sale_id) AS 
prev_amount_or_default
FROM lag_default_repro
ORDER BY region, sale_id;



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