如果利用相同的分组关键字或者没有分组关键字，来聚合多个列，那么，所有的聚合都在单个数据传递中的相同操作中进行。

If more than one column is aggregated using the same grouping key or without a grouping key, then all the aggregations are computed within the same operation with a single pass over the data.

youdao

检查标签中的列关键字，来确认列关键字已经被重新排序，并且与SQL查询返回的数据字段相符。

Check the column keys in the tag to make sure that the column keys are realigned to match the data fields returned by the SQL query.

youdao

如果使用可空的vargraphic列，那么1021字节的索引限制仍然是对的。

If you use a nullable VARGRAPHIC column instead, the 1021-byte index limitation is still true.

youdao