Yes. The general pattern is to add a ‘boolean supportsXxx()’ method to 
SqlDialect, and make the JdbcYyyRule not generate a JdbcYyy if the relational 
expression contains an xxx and this particular dialect does not support it. 
Then add a test to RelToSqlConverterTest that covers several dialects.

(In this case xxx = windowed aggregates, and yyy = Project.)

Julian


> On Feb 22, 2018, at 2:53 AM, Pavel Gubin <pgu...@icloud.com> wrote:
> 
> Not all JDBC datasources support window functions. But JdbcProject is 
> generated regardless of this fact. In the result we get SQL with window 
> function which gives an error when the execution is pushed to the JDBC 
> datasource. What is the best way to avoid such errors based on SQL dialect? 
> Avoid converting to JdbcProject if some unsupported features are used?
> 
> Pavel

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