如果 IN 列表中包含参数标记符或主机变量，使优化器不能使用编目统计信息来确定选择性，就会出现这种情况。

This can occur if the IN list contains parameter markers or host variables which prevent the optimizer from using catalog statistics to determine the selectivity.

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该标记列表—在实际的文档解析期间在特别基础上生成—用作结构示意图中使用的单字节标记占位符的索引。

This list of tags — generated on an AD hoc basis during the actual document parsing — was used as an index for single-byte tag placeholders used in a structure schematic.

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