Solr模式中的omitNorms和version字段是什么? [英] What is omitNorms and version field in solr schema?
问题描述
我不知道何时使用omitNorms ="true".我阅读了2-3个链接，但仍不清楚其含义.这是什么意思?设置为true以忽略与此字段相关的规范(这将禁用字段的长度规范化和索引时间提升，并节省了一些内存.)仅全文字段或需要索引时间提升的字段需要规范."在 http://wiki.apache.org/solr/SchemaXml 页面
I am not understanding when to use omitNorms="true". I read 2-3 links but still I am not clear with its meaning. what does it mean "Set to true to omit the norms associated with this field (this disables length normalization and index-time boosting for the field, and saves some memory). Only full-text fields or fields that need an index-time boost need norms." at http://wiki.apache.org/solr/SchemaXml page
推荐答案
规范按单字节信息存储在每个文档每个字段的索引中.这将保存应用于字段的索引时间提升的信息或长度"信息.
长度信息使您可以增加较短的字段，而不是较长的字段.
同样，索引时间提升将使一个字段比其他字段更高级.
Norms are stored as a Single byte information in the index per document per field. This will hold information for the index time boost applied to the field or Length information.
Length information would allow you to boost shorter fields more that longer fields.
Also, Index time boost will allow one field to be boosted higher then other.
由于占用空间，如果不需要，应将其关闭.
如果未使用索引时间提升，或者如果这些字段是短文本字段或不需要任何长度规范化的非文本字段，则为空.
As it takes up space, it should be turned off if not needed.
If no index time boost is used OR if the fields are short text fields or non-text fields which do not need any length normalization.
您可以在此处找到一些详细的说明.
You can find a little detailed explanation here.
将规范加载到IndexReader中时，会将它们加载到 每个字段的byte [maxdoc]数组-即使400个文档中也有一个 万有一个字段，它仍将为此加载byte [maxdoc] 字段，可能会占用大量RAM.
When norms are loaded up into an IndexReader, they are loaded into a byte[maxdoc] array for each field – so even if one document out of 400 million has a field, it is still going to load byte[maxdoc] for that field, potentially using a lot of RAM.
作为一个例子，我们讨论了多少RAM，十个字段中的一个 百万文档索引将占用不到10 MB的RAM.一百 这样的字段将占用近GB的RAM.
As an example of how much RAM we are talking about, one field in a 10 million doc index will take up just under 10 MB of RAM. One hundred such fields will take nearly a gigabyte of RAM.
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