[GitHub] [arrow-datafusion] alamb opened a new issue #1725: API to get Expr's type and nullability without a `DFSchema`

[GitBox <gi...@apache.org>]

alamb opened a new issue #1725:
URL: https://github.com/apache/arrow-datafusion/issues/1725


   **Is your feature request related to a problem or challenge? Please describe what you are trying to do.**
   I am trying to implement (fast) expression simplification that sits on the critical IOx query path (as the predicates get simplified and then used to prune out chunks based on catalog statistics)
   
   When i created a PR to use the API proposed in https://github.com/apache/arrow-datafusion/pull/1717 for simplify exprs, I found out that to get `is_boolean_type()` and `nullable` information from an `Expr` I needed to pass it a `DFSchema` (which is a kind of wrapper over a normal Arrow Schema). For us in IOx this involves a copy (as we have our own wrapper over Schema). 
   
   
   **Describe the solution you'd like**
   I would like to be able to use expression simplification without creating a new `DFSchema`.
   
   Specifically
   1. Add a trait that can provide the needed information for schema quries to Expr
   1. Change the functions on `Expr` that take a &DFSchema such as `Expr::nullable` to be nullable
   3. `impl` this new trait for `DFSchema` so that existing callsites work
   
   
   **Describe alternatives you've considered**
   N/A
   
   **Additional context**
   You can see the code here: https://github.com/influxdata/influxdb_iox/pull/3588/files#r796004295


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[GitHub] [arrow-datafusion] alamb closed issue #1725: API to get Expr's type and nullability without a `DFSchema`

[GitBox <gi...@apache.org>]

alamb closed issue #1725:
URL: https://github.com/apache/arrow-datafusion/issues/1725


   


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