During plan generation for the query, the query optimizer communicates with the non-relational wrapper.
在为查询生成计划的过程中，查询优化器与非关系包装器通信。
For relational nicknames, the wrapper validates the existence of the data source objects and retrieves the column definitions and index information, if any, when the nickname is defined.
对于关系昵称，包装器确认数据源对象是否存在，如果定义了昵称，还将获取列定义和索引信息。
During the registration step for relational nicknames, the wrapper modules try to retrieve remote catalog information for the underlying object.
在关系昵称的注册步骤中，包装器模块试图获取底层对象的远程编目信息。
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