November 2021
Intermediate to advanced
410 pages
12h 1m
Chinese
Content preview from MongoDB权威指南（第3版）
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28
｜
第
3
章
如果仔细研究这些示例，你可能会注意到，除了简单的插入之外，这两个对
insertMany
调
用的输出提示还有其他操作可能支持批量写入。虽然
insertMany
不支持插入以外的操作，
但
MongoDB
确实有一个批量写入
API
允许在单个调用中批量处理多个不同类型的操作
。
这部分内容超出了本章的范围，如果你感兴趣，可以在
MongoDB
的相关文档中查阅关于
批量写入
API
的内容。
3.1.2
插入校验
MongoDB
会对要插入的数据进行最基本的检查：检查文档的基本结构，如果不存在
"_id"
字段，则自动添加一个。其中一项最基本的结构检查就是文档大小：所有文档都必须小于
16MB
。这是一个人为设定的限制
（将来可能会提高），主要是为了防止不良的模式设计并
确保性能上的一致。要查看
doc
文档的二进制
JSON
（
BSON
）大小
（以字节为单位），可
以在
shell
中执行
Object.bsonsize(doc)
。
为了让你对
16MB
的数据量有个概念，以《战争与和平》为例，整部著作也只有
3.14MB
。
由于仅做最基本的检查，这意味着可以很容易地插入无效数据（如果你尝试这么做的话）。
因此，应该只允许受信任的源（比如应用程序服务器）连接到数据库。所有主流语言的
MongoDB
驱动程序以及大部分其他语言的驱动程序
，在向数据库发送任何内容之前，都会
进行各种无效数据的校验（比如文档过大、包含非
UTF-8
字符串，或使用无法识别的类型）
。
3.1.3
插入
在
MongoDB 3.0
之前，
insert
是在
MongoDB
中插入文档的主要方法。在 ...
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