Zoltan Haindrich created HIVE-22893:
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Summary: Enhance data size estimation for fields computed by UDFs
Key: HIVE-22893
URL: https://issues.apache.org/jira/browse/HIVE-22893
Project: Hive
Issue Type: Improvement
Components: Statistics
Reporter: Zoltan Haindrich
Assignee: Zoltan Haindrich
Right now if we have columnstat on a coumn ; we use that to estimate things
about the column; - however if an UDF is executed on a column ; the resulting
column is treated as unknown thing and defaults are assumed.
An impovement could be to give wide estimation(s) in case of frequently used
udf.
For example; consider {{substr(c,1,1)}} ; no matter what the input; the output
is at most a 1 long string
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