Solr * vs *:* 查询性能 [英] Solr * vs *:* query performance

问题描述

我们正在运行 Solr 3.4 并且有一个相对较小的索引，大约有 90,000 个文档.这些文档分为几个逻辑源，因此每次搜索都将应用针对特定源的过滤器查询，例如:

We're running Solr 3.4 and have a relatively small index of 90,000 documents or so. These documents are split over several logical sources, and so each search will have an applied filter query for a particular source, e.g:

?q=<query>&fq=source:<source>

其中 source 是一个经典的字符串字段.我们正在使用 edismax 并有一个默认搜索字段 text.

where source is a classic string field. We're using edismax and have a default search field text.

我们目前看到 q=* 的平均运行时间是 q=*:* 的 20 倍.差异非常明显，*:* 需要 100 毫秒，而 * 最多需要 3500 毫秒.在文档集中搜索一个常用词(匹配所有文档的近 50%)将在不到 200 毫秒内返回结果.

We are currently seeing q=* taking on average 20 times longer to run than q=*:*. The difference is quite noticeable, with *:* taking 100ms and * taking up to 3500ms. A search for a common word in the document set (matching nearly 50% of all documents) will return a result in less than 200ms.

查看启用了 debugQuery 的查询，我们可以看到 * 被解析为 DisjunctionMaxQuery((text:*))，而 *:* 被解析为 MatchAllDocsQuery(*:*).这是有道理的，但我仍然不认为它会导致这种幅度的放缓(与 50% 的文档匹配的内容相比，下降了 2000%).

Looking at the queries with debugQuery on, we can see that * is parsed to a DisjunctionMaxQuery((text:*)), while *:* is parsed to a MatchAllDocsQuery(*:*). This makes sense, but I still don't feel like it accounts for a slowdown of this magnitude (a slowdown of 2000% over something that matches 50% of the documents).

可能是什么原因造成的?有什么我们可以调整的吗?

What could be causing this? Is there anything we can tweak?

推荐答案

当您只传递 * 时，您正在命令检查字段中的每个值并将其与 *，还有很多工作要做.但是，当您使用 * : * 时，您要求 Solr 为您提供所有内容并跳过任何匹配.

When you are passing just * you are ordering to check every value in the field and match it against * and that is a lot to do. However when you are using * : * you are asking Solr to give you everything and skip any matching.

Solr/Lucene 经过优化，可以快速高效地执行 * : *！

Solr/Lucene is optimized to do * : * fast and efficient!

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