使用$indexOfCP检查子字符串中是否存在matchingWord。如果matchingWord不在子字符串中，则将返回-1.$map此结果从matchingWords数组返回到布尔数组。使用$anyElementTrue检查搜索字符串中的任何单词。
I needed my solution to be able to return multiple results of the subarray elements. Using $unwind + $match + $group resulted in losing root documents without matching array elements, which I didn't want to in my case because in fact I was only looking to filter out unwante...
Note that this only returns the first match for each document: if Bob had left multiple comments on this post, only the first one in the "comments" array would be returned. Array and range query interactions Scalars (non-array elements) in documents must match each clause of a query’s ...
So the $elemMatch with the $nin is finding the docs where a single element of the Stuff array is not in the set of strings, and then the parent $not inverts the match to return all the docs where that didn't match any elements. Starting with docs of: db.test.insert([ {Stuf...
MongoDBcreates separate index entriesfor*every*element of the array.These[multikey indexes]allow queries toselectdocuments that contain arrays by matching on element or elements of the arrays.MongoDBautomatically determines whether to create a multikey indexifthe indexed field contains an arrayvalue;...
Although the array field grades may contain multiple elements that are greater than or equal to 85, the $ projection operator returns only the first matching element from the array. Project Array Documents A students collection contains the following documents where the grades field is an array ...
If you index a field that holds an array value, MongoDB creates separate index entries for every element of the array. These multikey indexes allow queries to select documents that contain arrays by matching on element or elements of the arrays. MongoDB automatically determines whether to create...
MongoDB 主节点重启（MongDB Primary Node Restart）是指在 MongoDB 集群中，担任主节点的服务器发生故障...
These multikey indexes allow queries to select documents that contain arrays by matching on element or elements of the arrays. MongoDB automatically determines whether to create a multikey index if the indexed field contains an array value; you do not need to explicitly specify the multikey type...
I need to count the number of matching elements between 2 arrays using MongoDB filter aggregation. I tried using $eq and $setIntersection on the condition field of filter but the number of matching elements return just 1 even if all 4 elements match. Here's the user scenario: ...