MongoEngine在查询中指定读取首选项 [英] MongoEngine specify read preference on query

问题描述

我正在使用Mongo 2.6，Pymongo 2.7.2和Mongoengine 0.8.7.对于特定的读取查询，我想使用副本集的辅助查询.因此，如mongoengine文档中的此处我的查询如下:

I am using Mongo 2.6, Pymongo 2.7.2 and Mongoengine 0.8.7. For a particular read query, I want to use the secondary of my replica set. Hence, as specified in the mongoengine documentation here I wrote my query as follows :

from pymongo.read_preferences import ReadPreference    
<collection_name>.objects().read_preference(ReadPreference.SECONDARY_PREFERRED)

但是，查询总是看起来像是主数据库(此查询的日志始终仅在主数据库中可见).语法正确吗?如果是，如何验证是否正在查询辅助节点?

However, the query is always going to the primary it seems ( The logs for this query are always seen only in the primary ). Is the syntax correct? If yes, how do I verify if the secondary is being queried?

推荐答案

找出问题所在.在MongoEngine 连接" 方法中，需要按以下方式指定 replicaSet 参数:

Figured out what the issue was. In the MongoEngine "connect" method, the replicaSet parameter needed to be specified as follows:

connect(db = "my_db", replicaSet = "my_replica_set_name", host = "hostname", port = "port_number")

读取首选项的语法如上所述是正确的.传入 replicaSet 参数使其生效.

The syntax of the read preference is correct as specified above. Passing in the replicaSet parameter made it work.

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