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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特殊的索引和集合类型
｜
123
要查询附近的点，需要使用
"$near"
。临近查询会返回距离给定点最近的坐标对的文档，
并按照距离对结果进行排序。以下查询会找出
hyrule
集
合中所有的文档，并按照与点
[20, 21]
的距离进行排序：
> db.hyrule.find({"tile" : {"$near" : [20, 21]}})
如果没有指定，则默认限制最多返回
100
个文档。如果不需要那么多结果，则应该设置一
个限制来节省服务器端资源。例如，下面的代码会返回最接近
[20, 21]
的
10
个文档。
> db.hyrule.find({"tile" : {"$near" : [20, 21]}}).limit(10)
6.2
全文搜索索引
MongoDB
中的
text
索引支持全文搜索。这种类型的
text
索引不应该与
MongoDB Atlas
全
文搜索索引（
full-text
search index
）相混淆，不同于
MongoDB
文本索引，后者利用
Apache
Lucene
来提供额外的文本搜索功能
。如果应用程序允许用户提交关键字查询，而这些查询
与集合中的标题、描述和其他字段的文本相匹配，那么应该使用
text
索引。
前几章已经使用了精确匹配和正则表达式来对字符串进行查询，但是这些技术有一定的限
制。使用正则表达式来搜索大块文本会非常慢，而且很难解决词法（例如，“
entry
”应该
与“
entries
”匹配）以及人类语言所带来的其他挑战
。
text
索引可以快速搜索文本并提供
对一些常见搜索引擎需求（比如适合于语言的标记化、停止单词和词干提取）的支持。 ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.