在觀看ES文檔時做了一些基礎(chǔ)測試，在執(zhí)行以下操作時出現(xiàn)報錯

GET /megacorp/employee/_search
{
  "aggs":{
    "all_interests":{
      "terms": {
        "field": "interests"
      }
    }
  }
}

錯誤如下：

{
  "error": {
    "root_cause": [
      {
        "type": "illegal_argument_exception",
        "reason": "Fielddata is disabled on text fields by default. Set fielddata=true on [interests] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory. Alternatively use a keyword field instead."
      }
    ],
    "type": "search_phase_execution_exception",
    "reason": "all shards failed",
    "phase": "query",
    "grouped": true,
    "failed_shards": [
      {
        "shard": 0,
        "index": "megacorp",
        "node": "3DTOZs6yRsS8kxERdFJoHw",
        "reason": {
          "type": "illegal_argument_exception",
          "reason": "Fielddata is disabled on text fields by default. Set fielddata=true on [interests] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory. Alternatively use a keyword field instead."
        }
      }
    ],
    "caused_by": {
      "type": "illegal_argument_exception",
      "reason": "Fielddata is disabled on text fields by default. Set fielddata=true on [interests] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory. Alternatively use a keyword field instead.",
      "caused_by": {
        "type": "illegal_argument_exception",
        "reason": "Fielddata is disabled on text fields by default. Set fielddata=true on [interests] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory. Alternatively use a keyword field instead."
      }
    }
  },
  "status": 400
}

經(jīng)過查找驗證后發(fā)現(xiàn)出現(xiàn)該錯誤是因為5.x之后泽台，Elasticsearch對排序寻狂、聚合所依據(jù)的字段用單獨的數(shù)據(jù)結(jié)構(gòu)(fielddata)緩存到內(nèi)存里了蠕嫁，但是在text字段上默認是禁用的，如果有需要單獨開啟菊卷，這樣做的目的是為了節(jié)省內(nèi)存空間缔恳。

所以如果需要進行聚合操作，需要單獨開啟洁闰。

執(zhí)行以下代碼：

PUT megacorp/_mapping/employee/
{
  "properties": {
    "interests": { 
      "type":     "text",
      "fielddata": true
    }
  }
}

設(shè)置成功后會出現(xiàn)如下結(jié)果：

{
  "acknowledged" : true
}

再次執(zhí)行查詢后就出現(xiàn)想要的結(jié)果了歉甚。
轉(zhuǎn)自：https://blog.csdn.net/abandon_li/article/details/87285887