Elasticsearch nested sort filter 嵌套排序问题及解决
官方解释
首先来看一下官方文档：Sorting by Nested Fields
看不懂的没关系，它其实就只有两句是有用的，就是那两段代码。
索引
PUT /my_index/blogpost/2
{
"title": "Investment secrets",
"body": "What they don't tell you ...",
"tags": [ "shares", "equities" ],
"comments": [
{
"name": "Mary Brown",
"comment": "Lies, lies, lies",
"age": 42,
"stars": 1,
"date": "2014-10-18"
},
{
"name": "John Smith",
"comment": "You're making it up!",
"age": 28,
"stars": 2,
"date": "2014-10-16"
}
]
}嵌套查询
GET /_search
{
"query": {
"nested": {
"path": "comments",
"filter": {
"range": {
"comments.date": {
"gte": "2014-10-01",
"lt": "2014-11-01"
}
}
}
}
},
"sort": {
"comments.stars": {
"order": "asc",
"mode": "min",
"nested_filter": {
"range": {
"comments.date": {
"gte": "2014-10-01",
"lt": "2014-11-01"
}
}
}
}
}
}以上是官方代码，方便打不开网页的同学查看。下面是我遇到的问题及解决方法。
记录
这里只提供了RestfulAPI，我在使用java的过程中遇到了很多问题。有超过一半的时间都耗在这里了，特此记录一下。
问题
项目中使用java API，所以参照ResefulAPI写出来一段代码。
首先是有一段正确的restful 代码，这一段是仿照官方文档写的，运行后测试正确无误。
{
"sort": {
"goods_sale_number.sale_num": {
"order": "asc",
"nested_filter": {
"term": {
"warehouse_id": "22" }
},
"missing": "_last"
}
},
"size": "99999",
"_source": [
"goods_sale_number",
"id"
]
}错误的java代码，根据json转换的，运行后无法排序。
String flag = sortOrder.toString().equals("desc") ? "_last" : "_first";
FilterBuilder termFilter = FilterBuilders.termFilter("goods.goods_sale_number.warehouse_id", warehouseId);
searchRequestBuilder.addSort(SortBuilders.fieldSort("goods_sale_number.sale_num")
.setNestedFilter(FilterBuilders.nestedFilter("goods_sale_number", termFilter))
.setNestedPath("goods.goods_sale_number")
.order(sortOrder).missing(flag));乍一看，其实java代码和restful的代码并没有什么区别，但是却一直不能使用。
分析及解决问题
- 我尝试过各种各样的写法，改变访问的路径，切换过滤的类型，能试过的方法都试过了，但是还是不可以正确排序。
- 由于
SearchRequestBuilder类有一个方法可以直接setSource(String)，当然，它只能单独使用。如果还有其它的参数，可以使用searchRequestBuilder.setExtraSource(String)。所以我尝试把json的值放在这个函数里面使用，结果是正确的，正序逆序都是正确的。 - 猜测：可能是转换的过程中出错了。（由于elasticsearch 是基于lucene的，所以我猜测是json转换java的结果可能和我写的不一样。实际在查看代码后发现其实是把java代码转换成了json，放在了searchRequestBuilder.source里面）
elasticsearch源码分析
源码
package org.elasticsearch.action.search;
public class SearchRequestBuilder extends ActionRequestBuilder<SearchRequest, SearchResponse, SearchRequestBuilder, Client> {
...
//这个方法就是解决问题的根源
public SearchRequest request() {
if(this.sourceBuilder != null) {
((SearchRequest)this.request).source(this.sourceBuilder());
}
return (SearchRequest)this.request;
}
...
}
分析
在此我们可以看到有一个this.sourceBuilder()，它里面的值，就是我们写的java代码，query，filter，sort 等等都会在这里转换成json，写入到searchRequestBuilder.source，而searchRequestBuilder.extraSource则是之前我写入的另一部分json，得到这两部分值后对比一下。
//source
"sort" : [ {
"goods_sale_number.sale_num" : {
"order" : "desc",
"missing" : "_last",
"nested_filter" : {
"nested" : {
"filter" : {
"term" : {
"goods.goods_sale_number.warehouse_id" : "22"
}
},
"path" : "goods_sale_number"
}
},
"nested_path" : "goods.goods_sale_number"
}
} ]//extraSource
"sort": {
"goods_sale_number.sale_num": {
"order": "asc",
"nested_filter": {
"term": {
"warehouse_id": "22"
}
},
"missing": "_last"
}
}可以看到有明显的不同，不同就在于，中间多了几个nested的嵌套。所以分析出可能是由于对英文文档理解不当，sort里面的查询并非是嵌套查询，只是一个普通的查询。因为它本身在添加排序的时候就已经是嵌套了。
修改后的java代码：
String flag = sortOrder.toString().equals("desc") ? "_last" : "_first";
FilterBuilder termFilter = FilterBuilders.termFilter("warehouse_id", warehouseId);
searchRequestBuilder.addSort(SortBuilders.fieldSort("goods_sale_number.sale_num")
.setNestedFilter(termFilter)
.order(sortOrder).missing(flag));再次分析json：
//source
"sort" : [ {
"goods_sale_number.sale_num" : {
"order" : "desc",
"missing" : "_last",
"nested_filter" : {
"term" : {
"warehouse_id" : "22"
}
}
}
} ]这一次的值和restful API 的json一模一样了。再次执行后发现正确无误。
最终正确的代码
正确的java代码
String flag = sortOrder.toString().equals("desc") ? "_last" : "_first";
FilterBuilder termFilter = FilterBuilders.termFilter("warehouse_id", warehouseId);
searchRequestBuilder.addSort(SortBuilders.fieldSort("goods_sale_number.sale_num")
.setNestedFilter(termFilter)
.order(sortOrder).missing(flag));问题总结
- 把英文学好
- 遇到问题打断点
- 看源码
- 要有耐心
- 要细心
其间遇到的其它问题（child query must only match non-parent docs）
一个错误日志
[2015-10-20 18:15:25,553][DEBUG][action.search.type ] [local] [shop][4], node[uv2Ii94-R8a_Wk00s7bPew], [P], s[STARTED]: Failed to execute [org.elasticsearch.action.search.SearchRequest@1ba36675]
org.elasticsearch.search.query.QueryPhaseExecutionException: [shop][4]: query[ConstantScore(cache(+_type:goods +org.elasticsearch.index.search.nested.NonNestedDocsFilter@5005b052))],from[0],size[10],sort["goods_sale_number.sale_num": org.elasticsearch.index.fielddata.fieldcomparator.LongValuesComparatorSource@31026d4e>!]: Query Failed [Failed to execute main query]
at org.elasticsearch.search.query.QueryPhase.execute(QueryPhase.java:163)
at org.elasticsearch.search.SearchService.loadOrExecuteQueryPhase(SearchService.java:289)
at org.elasticsearch.search.SearchService.executeQueryPhase(SearchService.java:300)
at org.elasticsearch.search.action.SearchServiceTransportAction$5.call(SearchServiceTransportAction.java:231)
at org.elasticsearch.search.action.SearchServiceTransportAction$5.call(SearchServiceTransportAction.java:228)
at org.elasticsearch.search.action.SearchServiceTransportAction$23.run(SearchServiceTransportAction.java:559)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.elasticsearch.common.util.concurrent.UncheckedExecutionException: java.lang.IllegalStateException: child query must only match non-parent docs, but parent docID=1 matched childScorer=class org.apache.lucene.search.ConstantScoreQuery$ConstantScorer
at org.elasticsearch.common.cache.LocalCache$Segment.get(LocalCache.java:2203)
at org.elasticsearch.common.cache.LocalCache.get(LocalCache.java:3937)
at org.elasticsearch.common.cache.LocalCache$LocalManualCache.get(LocalCache.java:4739)
at org.elasticsearch.index.cache.fixedbitset.FixedBitSetFilterCache.getAndLoadIfNotPresent(FixedBitSetFilterCache.java:136)
at org.elasticsearch.index.cache.fixedbitset.FixedBitSetFilterCache.access$100(FixedBitSetFilterCache.java:73)
at org.elasticsearch.index.cache.fixedbitset.FixedBitSetFilterCache$FixedBitSetFilterWrapper.getDocIdSet(FixedBitSetFilterCache.java:218)
at org.elasticsearch.index.fielddata.IndexFieldData$XFieldComparatorSource$Nested.innerDocs(IndexFieldData.java:150)
at org.elasticsearch.index.fielddata.fieldcomparator.LongValuesComparatorSource$1.getLongValues(LongValuesComparatorSource.java:73)
at org.apache.lucene.search.FieldComparator$LongComparator.setNextReader(FieldComparator.java:716)
at org.apache.lucene.search.TopFieldCollector$OneComparatorNonScoringCollector.setNextReader(TopFieldCollector.java:97)
at org.elasticsearch.common.lucene.MultiCollector.setNextReader(MultiCollector.java:66)
at org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java:612)
at org.elasticsearch.search.internal.ContextIndexSearcher.search(ContextIndexSearcher.java:191)
at org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java:581)
at org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java:533)
at org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java:510)
at org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java:345)
at org.elasticsearch.search.query.QueryPhase.execute(QueryPhase.java:150)
... 8 more
Caused by: java.lang.IllegalStateException: child query must only match non-parent docs, but parent docID=1 matched childScorer=class org.apache.lucene.search.ConstantScoreQuery$ConstantScorer
at org.apache.lucene.search.join.ToParentBlockJoinQuery$BlockJoinScorer.nextDoc(ToParentBlockJoinQuery.java:286)
at org.elasticsearch.index.cache.fixedbitset.FixedBitSetFilterCache$2.call(FixedBitSetFilterCache.java:148)
at org.elasticsearch.index.cache.fixedbitset.FixedBitSetFilterCache$2.call(FixedBitSetFilterCache.java:136)
at org.elasticsearch.common.cache.LocalCache$LocalManualCache$1.load(LocalCache.java:4742)
at org.elasticsearch.common.cache.LocalCache$LoadingValueReference.loadFuture(LocalCache.java:3527)
at org.elasticsearch.common.cache.LocalCache$Segment.loadSync(LocalCache.java:2319)
at org.elasticsearch.common.cache.LocalCache$Segment.lockedGetOrLoad(LocalCache.java:2282)
at org.elasticsearch.common.cache.LocalCache$Segment.get(LocalCache.java:2197)
... 25 more 错误原因
当前嵌套的字段不在父级下面。
也就是，有一个shop索引（index），它有goods类型（type），然后它的属性（properties）里面有一个嵌套类型字段 sale_number （nested），它有两个字段叫 sale_number和 id，此时如果你使用 sale_number.sale_number 去访问这个字段是访问不到的，需要使用 goods.sale_number.sale_number，所以加上前面的type就可以了。但是这是在代码错误的时候遇到的错误的问题，仅此记录，它并不能在实际使用中经常遇到。