Guilherme Braccialli created HIVE-11741:
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Summary: Add a new hook to run before query parse/compile
Key: HIVE-11741
URL: https://issues.apache.org/jira/browse/HIVE-11741
Project: Hive
Issue Type: New Feature
Components: hpl/sql, Parser, SQL
Reporter: Guilherme Braccialli
Priority: Minor
It would be nice to allow developers to extend hive query language, making
possible to use custom wildcards on queries.
People uses Python or R to iterate over vectors or lists and create SQL
commands, this could be implemented directly on sql syntax.
For example this python script:
>>> sql = "SELECT state, "
>>> for i in range(10):
... sql += " sum(case when type = " + str(i) + " then value end) as
sum_of_" + str(i) + " ,"
...
>>> sql += " count(1) as total FROM table"
>>> print(sql)
Could be written directly in extended sql like this:
SELECT state,
%for id = 1 to 10%
sum(case when type = %id% then value end) as sum_of_%id%,
%end%
, count(1) as total
FROM table
GROUP BY state
This kind of extensibility can be easily added if we add a new hook after
VariableSubstitution call on Driver.compile method.
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