内容简介:在搜索引擎中,我们通常都是对域名(field)构建倒排索引(inverted index),实现了域值(Values)到文档(document)的映射,而DocValues则是构建了一个正向索引,实现文档到域值的映射。下面是官方给出的DocValues的介绍DocValues目前主要有五种类型,随后的博客中会一一详细介绍
DocValues
在搜索引擎中,我们通常都是对域名(field)构建倒排索引(inverted index),实现了域值(Values)到文档(document)的映射,而DocValues则是构建了一个正向索引,实现文档到域值的映射。下面是官方给出的DocValues的介绍 https://wiki.apache.org/solr/DocValues =
What docvalues are:
- NRT-compatible: These are per-segment datastructures built at index-time and designed to be efficient for the use case where data is changing rapidly.
- Basic query/filter support: You can do basic term, range, etc queries on docvalues fields without also indexing them, but these are constant-score only and typically slower. If you care about performance and scoring, index the field too.
- Better compression than fieldcache: Docvalues fields compress better than fieldcache, and "insanity" is impossible.
- Able to store data outside of heap memory: You can specify a different docValuesFormat on the fieldType (docValuesFormat="Disk") to only load minimal data on the heap, keeping other data structures on disk.
What docvalues are not:
- Not a replacement for stored fields: These are unrelated to stored fields in every way and instead datastructures for search (sort/facet/group/join/scoring).
- Not a huge improvement for a static index: If you have a completely static index, docvalues won't seem very interesting to you. On the other hand if you are fighting the fieldcache, read on.
- Not for the risk-averse: The integration with Solr is very new and probably still has some exciting bugs!
DocValues的类型
DocValues目前主要有五种类型,随后的博客中会一一详细介绍
以上就是本文的全部内容,希望本文的内容对大家的学习或者工作能带来一定的帮助,也希望大家多多支持 码农网
猜你喜欢:本站部分资源来源于网络,本站转载出于传递更多信息之目的,版权归原作者或者来源机构所有,如转载稿涉及版权问题,请联系我们。
Designing Web Navigation
James Kalbach / O'Reilly Media / 2007-8-15 / USD 49.99
Thoroughly rewritten for today's web environment, this bestselling book offers a fresh look at a fundamental topic of web site development: navigation design. Amid all the changes to the Web in the pa......一起来看看 《Designing Web Navigation》 这本书的介绍吧!