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。
ODPS权威指南
李妹芳 / 人民邮电出版社 / 2014-12 / 69元
ODPS（Open Data Processing Service）是阿里巴巴自主研发的海量数据处理和分析的服务平台，主要应用于数据分析、海量数据统计、数据挖掘、机器学习和商业智能等领域。目前，ODPS不仅在阿里内部得到广泛应用，享有很好的口碑，正逐步走向第三方开放市场。 本书是学习和掌握ODPS的权威指南，作者来自阿里ODPS团队。全书共13章，主要内容包括：ODPS入门、整体架构、数据通......一起来看看 《ODPS权威指南》 这本书的介绍吧!
