排序:在需要调用sort()来查询排序后的结果的时候,以分片Key的最左边的字段为依据,Mongos可以按照预先排序的结果来查询最少的分片,并且将结果信息返回给调用者。这样会花最少的时间和资源代价。 相反,如果在利用sort()来排序的时候,排序所依据的字段不是最左侧(起始)的分片Key,那么Mongos将不得不并行的将查询请求...
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db.mycoll.find(...).sort(...) db.mycoll.findOne([query]) db.mycoll.findAndModify( { update : ... , remove : bool [, query: {}, sort: {}, 'new': false] } ) db.mycoll.getDB() get DB object associated with collection db.mycoll.getPlanCache() get query plan cache associat...
Optimizes this query: db.posts.find().sort({timestamp:-1} ) Because MongoDB can read indexes in both ascending and descending order, the direction of a single-key index does not matter. Indexes support queries, update operations, and some phases of theaggregation pipeline. ...
-q,--query:代表查询条件; --skip:跳过指定数量的数据; --limit:读取指定数量的数据记录; --sort:对数据进行排序,可以通过参数指定排序的字段,并使用 1 和 -1 来指定排序的方式,其中 1 为升序排列,而-1是用于降序排列,如sort({KEY:1})。 测试 ...
6.1.4 $sort. 48 6.1.5 综合应用... 48 6.1.6 $unwind. 49 6.2 聚合命令... 50 6.2.1 count. 50 6.2.2 distinct. 50 7 GirdFS. 51 8 用户管理... 55 9 创建副本集... 55 9.1 MongoDB Atlas. 56 10 复制集(replication)... 63 ...
Query the query plan for a specified query. db.<collection>.getPlanCache().getPlansByQuery({"query": {"name": "testname"}, "sort": { "name": 1 }) queryHash and planCacheKey MongoDB 4.2 or later introduces queryHash to define query shapes. Each query shape is associated with a ...
A MongoDB Query projection.Depending on the projection, the returned documents either omit specific fields or include only specified fields and values. sort sort object A MongoDB Sort Expression. Matched documents are returned in ascending or descending order of the fields specified in the express...
MongoDB DocumentDB ORDER BY JetBrains Rider supports the ORDER BY clause. Instead of ORDER BY, you can use SORT BY. MongoDB DocumentDB LIMIT JetBrains Rider supports the LIMIT clause. MongoDB DocumentDB OFFSET JetBrains Rider supports OFFSET clause. MongoDB DocumentDBSQL...
MongoDB Aggregation Framework Query & CRUD Operations Aggregation Editor Take a look at how to build aggregation queries stage-by-stage with the Aggregation Editor, starting with this example that uses $match, $group and $sort. Posted on: 02/06/2020 (last updated: 27/02/2025) • Kirsty...