Paul Rogers created IMPALA-7766:
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Summary: Perform constant folding within an expression
Key: IMPALA-7766
URL: https://issues.apache.org/jira/browse/IMPALA-7766
Project: IMPALA
Issue Type: Improvement
Components: Frontend
Affects Versions: Impala 3.0
Reporter: Paul Rogers
Suppose we have the following query:
{code:sql}
SELECT id + 1 + 2, 2 + 3 FROM foo;
{code}
Then, examine the SELECT after rewrites (using the new {{FullRewriteTest}}.)
We'd expect content folding. However, constant folding only happens if the
entire expression is constant, it can't handle sub-expressions. Result:
{code:sql}
SELECT id + 1 + 2, 5 FROM foo;
{code}
Constant folding within an expression is tricky, and it is not clear what, if
any, performance gain would be had. Still, it is worth keeping in mind.
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