sgrebnov opened a new issue, #11325:
URL: https://github.com/apache/datafusion/issues/11325

   ### Is your feature request related to a problem or challenge?
   
   Part of https://github.com/apache/datafusion/issues/9494 to enhance support 
for Unparsing LogicalPlan to SQL String.
   
   Converting LogicalPlans back to SQL is valuable for several usecases such as 
using DataFusion in federated databases (e.g. generate SQL to push down) or 
using DataFusion's expr APIs to programmatically create SQL.
   
   ### Describe the solution you'd like
   
   The logical plan derived from queries with time predicates like those below 
(involving string literals and function result casting to timestamp) should be 
able to be turned back into SQL. Currently, they are failing with `Unsupported 
DataType: conversion: Timestamp(Nanosecond, None)`.
   
   ```sql
   select * from taxi_trips where pickup_datetime > now()
   select * from taxi_trips where pickup_datetime = '2013-08-22 06:24:12-02'
   ```
   
   ### Describe alternatives you've considered
   
   1. Implement the arrow to ast cast support for timestamp in 
Unparser::expr_to_sql([source 
link](https://github.com/apache/datafusion/blob/16346022ed4564211c0fb4bf20ac165f2c481a90/datafusion/sql/src/unparser/expr.rs#L200-L205))
   1. Add a test to 
[expr_to_sql_ok](https://github.com/apache/datafusion/blob/16346022ed4564211c0fb4bf20ac165f2c481a90/datafusion/sql/src/unparser/expr.rs#L912-L913)
   
   ### Additional context
   
   Example issue when using DataFusion with federated database : 
https://github.com/spiceai/spiceai/issues/1625


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