Why isn't the GROUP BY operator evaluated remotely?
There are several areas that you can check to determine why a GROUP BY operator is not evaluated remotely.
The areas that you can check include:
- Is the input to the GROUP BY operator evaluated remotely? If the answer is no, examine the input.
- Does the data source have any restrictions on this operator? Examples
- Limited number of GROUP BY items
- Limited byte counts of combined GROUP BY items
- Column specification only on the GROUP BY list
- Does the data source support this SQL operator?
- Global optimization. The optimizer decided that local processing is more cost-effective.