Question

我正在尝试进行简单的查询：

entity = DeviceLocation.query(ndb.StringProperty('deviceID') == data['deviceID']).order(-DeviceLocation.timestamp).get()

每次引发下一个错误：

NeedIndexError: no matching index found. recommended index is:
- kind: DeviceLocation
  properties:
  - name: deviceID
  - name: timestamp

问题是，即使我正在尝试创建索引（由此引导 - https://cloud.google.com/appengine/docs/python/datastore/indexes），部署命令（gcloud app deloy index.yaml）也会返回此信息：

ERROR: (gcloud.app.deploy) Server responded with code [400]:
  Bad Request Unexpected HTTP status 400.
  Creating a composite index failed for entity_type: "DeviceLocation"
ancestor: false
Property {
  name: "timestamp"
  direction: 2
}
: This index:
IndexDef{form=SCANNER_BUILTIN_SINGLE_PROPERTY, kind=DeviceLocation, isAncestor=false, propertyDefs=[PropertyDef{path=timestamp, direction=DESCENDING, mode=null}]}
is not necessary, since single-property indices are built in. Please remove it from your index file and upgrade to the latest version of the SDK, if you haven't already.

据我了解，错误之间存在矛盾。这与group_by和projection相关。

目前，无法运行任何复杂的查询，这会阻止我取得任何进展。

Answer 1

实际上这不是一个简单的查询＆＃39;因为您按deviceID过滤并按timestamp排序。

GAE指示您创建复合索引，这是您必须附加到index.yaml文件的内容：

- kind: DeviceLocation
  properties:
  - name: deviceID
  - name: timestamp

确保按此特定顺序包含这两个属性（deviceID和timestamp）。

要改进的最后一件事是您按财产过滤的方式：

DeviceLocation.deviceID == data['deviceID']

Google App Engine - NeedIndexError：找不到匹配的索引

1 个答案: