ElasticSearch最佳入门实践（三十九）倒排索引核心原理揭秘

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1、例子，两段文本

doc1：I really liked my small dogs, and I think my mom also liked them

doc2：He never liked any dogs, so I hope that my mom will not expect me to liked him.

2、初步的倒排索引的建立

演示倒排索引最简单的建立的一个过程

work	doc1	doc2
I	*	*
really	*
liked	*	*
my	*	*
small	*
dogs	*
and	*
think	*
mom	*	*
also	*
them	*
He		*
never		*
any		*
so		*
hope		*
that		*
will		*
not		*
expect		*
me		*
to		*
him		*

搜索
mother like little dog，不可能有任何结果
mother
like
little
dog

这个是不是我们想要的搜索结果？？？绝对不是，因为在我们看来，mother和mom有区别吗？同义词，都是妈妈的意思。like和liked有区别吗？没有，都是喜欢的意思，只不过一个是现在时，一个是过去时。little和small有区别吗？同义词，都是小小的。dog和dogs有区别吗？狗，只不过一个是单数，一个是复数。

normalization，建立倒排索引的时候，会执行一个操作，也就是说对拆分出的各个单词进行相应的处理，以提升后面搜索的时候能够搜索到相关联的文档的概率
时态的转换，单复数的转换，同义词的转换，大小写的转换
mom —> mother
liked —> like
small —> little
dogs —> dog

3、重新建立倒排索引，加入normalization，再次用mother liked little dog搜索，就可以搜索到了

work	doc1	doc2
I	*	*
really	*
like	*	*
my	*	*
little	*
dog	*
and	*
think	*
mom	*	*
also	*
them	*
He		*
never		*
any		*
so		*
hope		*
that		*
will		*
not		*
expect		*
me		*
to		*
him		*

mother like little dog，分词，normalization
mother --> mom
like --> like
little --> little
dog --> dog
doc1和doc2都会搜索出来