To illustrate this, compare it to the predicate that is applied to the index scan numbered 5 in the plan, which is on the one and only column of the index on the child table.

为了展示这一点，将它与计划中第5号索引扫描上使用的谓词相比较，它针对子表中惟一的索引列。

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When creating a foreign key, Informix automatically creates a B-Tree index on the child table when creating a foreign key.

创建一个外键时，Informix 自动地在子表上创建一个 B-Tree 索引。

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Specifies the expression based on fields in the parent table that relates to an index in the child table.

指定基于父表中的字段而又与子表中的索引相关的表达式。

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