If there is an index on the join column, the costs will be significantly less; otherwise the database server must perform table scans for all tables, both outer and inner tables.

如果连接列上有一个索引，那么其成本会相当低；否则，数据库服务器就必须对所有表(外部和内部表)执行表扫描。

youdao

Also, DB2 cannot use random order index columns as part of a sort merge join.

另外，DB 2无法在排序合并合并连接中使用随机顺序的索引列。

youdao

Therefore, DB2 can use a DOUBLE index for faster join processing.

因此，DB 2可以使用DOUBLE索引用于快速连接处理。

youdao

He spent much of his life doing generous things, but just enough doing reckless things to join the long index of scandals and self-destruction in untold Kennedy histories to come.

CNN: Tragedy Strikes Again

The higher the index, the readier a country is to join.

ECONOMIST: EU ENLARGEMENT