mongodb-query

问题 Objective Find out possible differences in the following MongoDB queries and understand why one of them works and the other doesn't. Background A while ago I posted a questions asking for help regarding a MongoDB query: Using $push with $group with pymongo In that question my query didn't work, and I was looking for a way to fix it. I had a ton of help in the comments, and eventually found out the solution, but no one seems to be able to explain me why my first incorrect query doesn't work,

问题 I have assigned person, status inside my collection simply like below. [ {"ASSIGN_ID": "583f84bce58725f76b322398", "SPEC_ID" : "58411771", "STATUS": 1, "UPDATE_DATE": ISODate("2016-12-21T04:10:23.000Z")}, {"ASSIGN_ID": "583f84bce58725f76b322398", "SPEC_ID" : "58411772", "STATUS": 4, "UPDATE_DATE": ISODate("2016-12-22T04:10:23.000Z")}, {"ASSIGN_ID": "583f84bce58725f76b322398", "SPEC_ID" : "58411774", "STATUS": 4, "UPDATE_DATE": ISODate("2016-12-23T04:10:23.000Z")}, {"ASSIGN_ID":

问题 I'd like to apply some simple String manipulation when doing $project, is it possible to apply something like the following function on $project? : var themeIdFromZipUrl = function(zipUrl){ return zipUrl.match(/.*\/(T\d+)\/.*/)[1] }; I'm using the following query: db.clientRequest.aggregate( { $match: { "l": {$regex: ".*zip"}, "t": { "$gte": new Date('1/SEP/2013'), "$lte": new Date('7/OCT/2013') } } }, { $project: {"theme_url" : "$l", "_id": 0, "time": "$t"} }, { $group: { _id: { theme_url: "

问题 Can we add some custom field with static value to mongodb find query? I am trying to add/append API request UId to all the queries that we are making to mongodb, so that we can map requests with slow queries from mongodb logs. I am doing it in aggregate queries by using '$literal' in projected fields. My Aggregate queries looks something like : db.test.aggregate({ $project: { "custom_id": { $literal: "uid" } .. } .. }) Also I can't include each field individually in projected fields and add

问题 Suppose I want to search through a collection, scan the returned result set and return some transformation of it. I've tried the following code: db.my_collection.find({timestamp : {$gt: 1343032491799}}, {_id:0,sid:1}).limit(20).forEach(function(element) { print(element.sid); }) Ok, it worked well. To the question: how can I accumulate the results ( sid s) into an array instead of just printing them? Update : ruby-style one-liner is preferred (but not required) of course 回答1: Call toArray on

问题 I am running on Mongodb 3.6. Below is the structure of my document, which stores monthly rate information for list of products: { "_id": 12345, "_class": "com.example.ProductRates", "rates": [ { "productId": NumberInt(1234), "rate": 100.0, "rateCardId": NumberInt(1), "month": NumberInt(201801) }, { "productId": NumberInt(1234), "rate": 200.0, "rateCardId": NumberInt(1), "month": NumberInt(201802) }, { "productId": NumberInt(1234), "rate": 400.0, "rateCardId": NumberInt(2), "month": NumberInt

问题 Consider the following document: { "item1" : [ { "a" : 1, "b" : 2 } ], "item2" : [ "a", "b" ] } The following query: db.test.aggregate([ { "$project": { "items": { "$setIntersection": [ "$item1", "$item2" ] } }} ]) returns the expected result: { "_id" : ObjectId("5710785387756a4a75cbe0d1"), "a" : [ ] } If the document looks like this: { "item2" : [ "a", "b" ] } Then: db.test.aggregate([ { "$project": { "a": { "$setIntersection": [ "$item2", [ "a" ] ] } } } ]) Yields: { "_id" : ObjectId(

问题 Can someone please help me with creation of unique index @ mongoDB for the following condition ? Suppose I have a schema like this, and I want a unique compound index on 1.path 2.verb 3."switches.name" 4."switches.value" { "path": "somepath", "verb": "GET", "switches": [ { "name": "id", "value":"123" }, { "name": "age", "value":"25" } ] } So if I try to insert { "path": "somepath", "verb": "GET", "switches": [ { "name": "id", "value":"123" }, { "name": "age", "value":"25" } ] } I should get

问题 How can I get multiple sort in MongoDB with Perl? My current approach looks something like this: my $sort = {"is_instock" => -1, "ua" => 1}; my $resultSet = $collection ->find({moderated => 1, markers => {'$all'=>$obj->{markers}}}) ->sort($sort) ->limit(25); @{$result} = $resultSet->all; But, i got array sorted by one field(ua). What i did wrong? 回答1: The basic problem here is that a "hash" in Perl is ordered by "key" by default. In order to get the "order of insertion" you need to use Tie:

问题 I have about 200 mongodb databases. Every database has a collection called 'Group' and in this collection there is a field called 'meldingId'. Is it possible to make a one mongodb query which find all values in the different databases. (I managed to select the databases bij looping through the databases by selectDB($database_name)) 回答1: In Mongo shell, this can be done by using db.getSiblingDB() method to switch to admin database and get a list of the 200 databases by running the admin