[GitHub] [arrow-datafusion] alamb commented on issue #533: Add extension plugin to parse SQL into logical plan / user defined SQL

[GitBox]

alamb commented on issue #533:
URL: 
https://github.com/apache/arrow-datafusion/issues/533#issuecomment-1221293517

   An extension planner then looks like
   
   ```rust
   struct MySqlPlanner {
   }
   
   impl QueryPlanner for MySqlPlanner {
     // override expression planning
     fn plan_expr(&mut self, expr: sqlparser::ast::Expr) -> Expr {
       if need_to_rewrite(expr) {
           // custom planning logic
        } else {
          // fall back to default impl
          plan_expr(self, expr)
        }
     }
   }
   
   ```
   
   The issue with this approach is that it complicates the sql planner non 
trivially , so I am not sure it is a great idea


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