andygrove opened a new issue #1890:
URL: https://github.com/apache/arrow-datafusion/issues/1890


   **Is your feature request related to a problem or challenge? Please describe 
what you are trying to do.**
   I would like DataFusion to support the `coalesce` SQL function.
   
   Here is the [Postgres 
documentation](https://www.postgresql.org/docs/8.1/functions-conditional.html) 
for this function:
   
   ## 9.13.2. COALESCE
   
   ``` sql
   COALESCE(value [, ...])
   ```
   
   The COALESCE function returns the first of its arguments that is not null. 
Null is returned only if all arguments are null. It is often used to substitute 
a default value for null values when data is retrieved for display, for example:
   
   ``` sql
   SELECT COALESCE(description, short_description, '(none)') ...
   ```
   
   Like a CASE expression, COALESCE will not evaluate arguments that are not 
needed to determine the result; that is, arguments to the right of the first 
non-null argument are not evaluated. This SQL-standard function provides 
capabilities similar to NVL and IFNULL, which are used in some other database 
systems.
   
   **Describe the solution you'd like**
   As described above.
   
   **Describe alternatives you've considered**
   None
   
   **Additional context**
   This function is required by some of the queries in the TPC-DS benchmark.
   


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