Alibabacloud, Database, Query Optimization, Sql, Relational Databases.
t2 Where t1.c1 = t2.c1 group by t2.c1 ) Subquery Related Optimization Rules On the one hand, the characteristics of the correlatedjoin operator provide some information for optimization. For example: The row number after the correlatedjoin operator is the same as that in the left subtree. The