Dandandan opened a new issue #237:
URL: https://github.com/apache/arrow-datafusion/issues/237


   **Is your feature request related to a problem or challenge? Please describe 
what you are trying to do.**
   The (logical) optimizer contains some support for folding (boolean) 
constants. This can help, especially with other optimization passes, to 
optimize queries. For example, `LIMIT (0 + 0)` could be optimized first to 
`LIMIT 0`, to enable eliminating the whole plan.
   
   We should try to extend this support to most datatypes & expressions.
   
   **Describe the solution you'd like**
   `Expr`s can already be evaluated against a `RecordBatch`, and there is code 
to evaluate scalar values without going through Arrow. To make sure that the 
constant evaluation is implemented correctly & the same as the evaluation code, 
we should be able to reuse the code from there.
   
   **Describe alternatives you've considered**
   Manually implement the constant folding support. Downside here is that we 
end up with two implementations, which has a higher maintenance burden.
   
   **Additional context**
   Not in scope: add it to physical optimizer too. Here it could help too, 
especially if we have support for partitions.
   


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