Solr 分组查询分页无法正常工作。 [Solr、Lucene]

Question

我按字段 family 对我的 solr 文档进行了分组。获取前 20 个组的 solr 查询如下

/select?q=*:*&group=true&group.field=family&group.ngroups=true&start=0&group.limit=1

本次查询结果为20组如下

responseHeader: {
 zkConnected: true,
 status: 0,
 QTime: 1260,
 params: {
  q: "*:*",
  group.limit: "1",
  start: "0",
  group.ngroups: "true",
  group.field: "family",
  group: "true"
 }
},
grouped: {
 family: {
 matches: 464779,
 ngroups: 396324,
 groups: [
 {
   groupValue: "__fam__ME.EA.HE.728928",
   doclist: {
   numFound: 1,
   start: 0,
   maxScore: 1,
   docs: [
   {
    sku: "ME.EA.HE.728928",
    title: "Rexton Pocket Family Hearing Instrument Fusion",
    family: "__fam__ME.EA.HE.728928",
    brand: "Rexton",
    brandId: "6739",
    inStock: false,
    bulkDiscount: false,
    quoteOnly: false,
    cats: [
     "Hearing Machine & Components",
     "Health & Personal Care",
     "Medical Supplies & Equipment"
    ],
    leafCatIds: [
     "6038"
    ],
    parentCatIds: [
     "6259",
     "4913"
    ],
    Type__attr__: "Pocket Family",
    Type of Products__attr__: "Hearing Instrument",
    price: 3790,
    discount: 40,
    createdAt: "2016-02-18T04:51:36Z",
    moq: 1,
    offerPrice: 2255,
    suggestKeywords: [
     "Rexton",
     "Pocket Family",
     "Rexton Pocket Family"
    ],
    suggestPayload: "6038,Hearing Machine & Components",
    _version_: 1548082328946868200
   }
  ]
 }
},

在此结果中需要注意的是 ngroups 的值，即 396324

但是当我想获取最后一页的数据时，我会在 Solr 上点击这个查询

select?q=*:*&group=true&group.field=family&group.ngroups=true&start=396320&group.limit=1

{
 responseHeader: {
 zkConnected: true,
 status: 0,
 QTime: 5238,
 params: {
  q: "*:*",
  group.limit: "1",
  start: "396320",
  group.ngroups: "true",
  group.field: "family",
  group: "true"
  }
 },
 grouped: {
  family: {
   matches: 464779,
   ngroups: 396324,
   groups: [ ]
   }
  }
 }

当我将开始设置为 396320 时，结果为

0。结果中必须有 5 个文档。实际组数386887。为什么 ngroups 不正确？

顺便说一句，这个问题不存在于我设置的本地 solr 服务器中。刚刚出现在测试环境的 solr 云中

Answer 1

这是 grouping across distributed nodes 的一个已知问题（在 SolrCloud 模式下会发生这种情况）：

Grouping is supported for distributed searches, with some caveats:

Currently group.func is is not supported in any distributed searches

group.ngroups and group.facet require that all documents in each group must be co-located on the same shard in order for accurate counts to be returned. Document routing via composite keys can be a useful solution in many situations.

最直接的解决方案是使用家族作为路由键的一部分，确保所有相同的家族值最终都在同一个节点上。由于与节点数量相比，不同系列值的数量似乎非常多，因此这仍应确保您在节点之间有良好的文档分布。

根据您实际尝试做的事情，可能还有其他替代解决方案（如果您只想计数，使用 JSON facet 可能是一个不错的解决方案）。

Solr 分组查询分页无法正常工作。 [Solr、Lucene]

Solr grouped query pagination not working properly. [Solr, Lucene]

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solr

solrcloud