为何RESTHeart 5.1.5 POST新增文档时MongoDB仍检查_etag？

使用RESTHeart 5.1.5，通过HTTP POST请求向myapp集合新增文档，请求地址：

POST http://xyz:9998/logs/myapp?checkETag=false

请求体：

{
  "diff": {
    "address": {
      "addressLine2": [
        "152 Broadway, Suite 600",
        "150 Broadway, Suite 600"
      ]
    }
  },
  "tracking": {
    "resourceId": "2f9af48b-2a7c-47ce-bccc-0b29c1188648",
    "login": "MYDOMAIN\user1",
    "timestamp": "2024-04-08T15:01:28.671Z"
  }
}

但性能极差，MongoDB执行findAndModify时对集合做全文档扫描（尽管是POST请求），慢查询日志如下：

{
  "t": {
    "$date": "2024-04-08T17:01:28.731+02:00"
  },
  "s": "I",
  "c": "COMMAND",
  "id": 51803,
  "ctx": "conn29",
  "msg": "Slow query",
  "attr": {
    "type": "command",
    "ns": "logs.myapp",
    "command": {
      "findAndModify": "myapp",
      "query": {
        "_etag": {
          "$oid": "661406338bd44174052a37a9"
        }
      },
      "new": true,
      "upsert": true,
      "update": {
        "diff": {
          "address": {
            "addressLine2": [
              "152 Broadway, Suite 600",
              "150 Broadway, Suite 600"
            ]
          }
        },
        "tracking": {
          "resourceId": "2f9af48b-2a7c-47ce-bccc-0b29c1188648",
          "login": "MYDOMAIN\\user1",
          "timestamp": "2024-04-08T15:01:28.671Z"
        },
        "_etag": {
          "$oid": "661406c88bd44174052a37aa"
        }
      },
      "$db": "logs"
    },
    "planSummary": "COLLSCAN",
    "keysExamined": 0,
    "docsExamined": 2766646,
    "nMatched": 0,
    "nModified": 0,
    "upsert": true,
    "keysInserted": 2,
    "numYields": 2766,
    "queryHash": "EE3A823E",
    "planCacheKey": "EE3A823E",
    "reslen": 611,
    "locks": {
      "ParallelBatchWriterMode": {
        "acquireCount": {
          "r": 2767
        }
      },
      "FeatureCompatibilityVersion": {
        "acquireCount": {
          "w": 2767
        }
      },
      "ReplicationStateTransition": {
        "acquireCount": {
          "w": 2767
        }
      },
      "Global": {
        "acquireCount": {
          "w": 2767
        }
      },
      "Database": {
        "acquireCount": {
          "w": 2767
        }
      },
      "Collection": {
        "acquireCount": {
          "w": 2767
        }
      },
      "Mutex": {
        "acquireCount": {
          "r": 1
        }
      }
    },
    "flowControl": {
      "acquireCount": 2767,
      "timeAcquiringMicros": 1030
    },
    "storage": {
      "data": {
        "bytesRead": 101067941,
        "timeReadingMicros": 96970
      }
    },
    "protocol": "op_msg",
    "durationMillis": 1593
  }
}

已尝试在URL中添加checkETag=false参数，但无效果，求解决方法。

• 强制指定插入模式：在请求URL中添加mode=insert参数，绕过RESTHeart默认的upsert逻辑，直接执行插入操作，避免触发findAndModify：

  POST http://xyz:9998/logs/myapp?mode=insert&checkETag=false
  

• 为_etag创建索引：如果业务需要保留upsert逻辑，为_etag字段创建唯一索引，让MongoDB通过索引快速定位文档，消除全集合扫描：

  db.myapp.createIndex({ "_etag": 1 }, { unique: true })
  

• 检查集合写入配置：确认RESTHeart中集合的writeMode配置为insert，而非默认的upsert，避免自动触发更新逻辑。
• 升级RESTHeart版本：5.1.5可能存在checkETag=false参数失效的bug，升级到5.x系列较新版本（如5.4.x），修复ETag相关逻辑问题。

内容的提问来源于stack exchange，提问作者T.Rex