ES進行如下聚合操作時，會報如題所示錯誤：
1 ➜ Downloads curl -XPOST 'localhost:9200/bank/_search?pretty' -d ' 2 { 3 "size": 0, 4 "aggs": { 5 "group_by_state": { 6 "terms": { 7 "field": "state" 8 } 9 } 10 } 11 }'
提示報錯如下：
1 { 2 "error" : { 3 "root_cause" : [ 4 { 5 "type" : "illegal_argument_exception", 6 "reason" : "Fielddata is disabled on text fields by default. Set fielddata=true on [state] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory."
7 } 8 ], 9 "type" : "search_phase_execution_exception", 10 "reason" : "all shards failed", 11 "phase" : "query", 12 "grouped" : true, 13 "failed_shards" : [ 14 { 15 "shard" : 0, 16 "index" : "bank", 17 "node" : "nkL8C69pTMuXrZBXicjshw", 18 "reason" : { 19 "type" : "illegal_argument_exception", 20 "reason" : "Fielddata is disabled on text fields by default. Set fielddata=true on [state] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory."
21 } 22 } 23 ], 24 "caused_by" : { 25 "type" : "illegal_argument_exception", 26 "reason" : "Fielddata is disabled on text fields by default. Set fielddata=true on [state] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory."
27 } 28 }, 29 "status" : 400
30 }
根據官方文檔顯示，出現該錯誤是因為5.x之后，Elasticsearch對排序、聚合所依據的字段用單獨的數據結構(fielddata)緩存到內存里了，但是在text字段上默認是禁用的，如果有需要單獨開啟，這樣做的目的是為了節省內存空間。——官方文檔地址：https://www.elastic.co/guide/en/elasticsearch/reference/current/fielddata.html
開啟方法：
1 ➜ Downloads curl -XPUT 'http://localhost:9200/bank/_mapping/account' -d ' 2 { 3 "properties": { 4 "state": { 5 "type": "text", 6 "fielddata": true 7 } 8 } 9 }'
# bank是index、account是類型、state是你需要設置的text字段
出現如下提示，說明設置成功：
1 {"acknowledged":true}
至此，聚合問題解決：
1 ➜ Downloads curl -XPOST 'localhost:9200/bank/_search?pretty' -d ' 2 { 3 "size": 0, 4 "aggs": { 5 "group_by_state": { 6 "terms": { 7 "field": "state" 8 } 9 } 10 } 11 }' 12 { 13 "took" : 60, 14 "timed_out" : false, 15 "_shards" : { 16 "total" : 5, 17 "successful" : 5, 18 "failed" : 0 19 }, 20 "hits" : { 21 "total" : 1000, 22 "max_score" : 0.0, 23 "hits" : [ ] 24 }, 25 "aggregations" : { 26 "group_by_state" : { 27 "doc_count_error_upper_bound" : 20, 28 "sum_other_doc_count" : 770, 29 "buckets" : [ 30 { 31 "key" : "id", 32 "doc_count" : 27
33 }, 34 { 35 "key" : "tx", 36 "doc_count" : 27
37 }, 38 { 39 "key" : "al", 40 "doc_count" : 25
41 }, 42 { 43 "key" : "md", 44 "doc_count" : 25
45 }, 46 { 47 "key" : "tn", 48 "doc_count" : 23
49 }, 50 { 51 "key" : "ma", 52 "doc_count" : 21
53 }, 54 { 55 "key" : "nc", 56 "doc_count" : 21
57 }, 58 { 59 "key" : "nd", 60 "doc_count" : 21
61 }, 62 { 63 "key" : "me", 64 "doc_count" : 20
65 }, 66 { 67 "key" : "mo", 68 "doc_count" : 20
69 } 70 ] 71 } 72 } 73 }