Sergey Zadoroshnyak created HIVE-13951:
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Summary: GenericUDFArray should constant fold at compile time
Key: HIVE-13951
URL: https://issues.apache.org/jira/browse/HIVE-13951
Project: Hive
Issue Type: Bug
Components: UDF
Affects Versions: 1.3.0, 2.1.0
Reporter: Sergey Zadoroshnyak
1. Hive constant propagation optimizer is enabled.
hive.optimize.constant.propagation=true;
2. Hive query:
select array('Total','Total') from some_table;
ERROR: org.apache.hadoop.hive.ql.optimizer.ConstantPropagateProcFactory
(ConstantPropagateProcFactory.java:evaluateFunction(939)) - Unable to evaluate
org.apache.hadoop.hive.ql.udf.generic.GenericUDFArray@3d26c423. Return value
unrecoginizable.
Details:
During compilation of query, hive checks if any subexpression of a specified
expression can be evaluated to be constant and replaces such subexpression with
the constant.
If the expression is a deterministic UDF and all the subexpressions are
constants, the value will be calculated immediately during compilation time
(not runtime)
So array is a deterministic UDF, 'Total' is string constant. So Hive tries to
replace result of evaluation UDF with the constant.
But looks like, that Hive only supports primitives and struct objects.
So, array is not supported yet.
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