This question already has answers here:
compare two fields of same document [duplicate]
(1 answer)
MongoDb query condition on comparing 2 fields
(4 answers)
Closed 3 years ago.
This is the result of an aggregate query,
{
"_id" : ObjectId("5dab3240dfbe9a15cd69771d"),
"isManual" : false,
"frequency" : 60,
"lastExecuted" : ISODate("2019-10-21T03:38:15.114Z"),
"lastExecutedTimeFromNow" : 129.58105
}
{
"_id" : ObjectId("5dad47c65310a16581cc6294"),
"isManual" : false,
"frequency" : 50,
"lastExecuted" : ISODate("2019-10-25T00:00:00.000Z"),
"lastExecutedTimeFromNow" : 100
}
{
"_id" : ObjectId("5dad48a55310a16581cc6332"),
"isManual" : true,
"frequency" : 100,
"lastExecuted" : ISODate("2019-10-23T00:00:00.000Z"),
"lastExecutedTimeFromNow" : 50
}
I wanted to filter the documents where the field lastExecutedTimeFromNow greater than frequency. But it returns 0 results.
Here's the aggregate query I'm using,
db.getCollection('test').aggregate([
{
$match: {
"lastExecutedTimeFromNow": { $gte: "$frequency" }
}
}
])
Any clue on where I'm going wrong or any help on this would really be great.
You can use $expr but keep in mind it's slower than normal $match
db.getCollection('test').aggregate([
{
$match: {
$expr: {
$gte: [
"$lastExecutedTimeFromNow",
"$frequency"
]
}
}
}
])
Related
Is there a possibility to calculate mathematical operation on already aggregated computed fields?
I have something like this:
([
{
"$unwind" : {
"path" : "$users"
}
},
{
"$match" : {
"users.r" : {
"$exists" : true
}
}
},
{
"$group" : {
"_id" : "$users.r",
"count" : {
"$sum" : 1
}
}
},
])
Which gives an output as:
{ "_id" : "A", "count" : 7 }
{ "_id" : "B", "count" : 49 }
Now I want to divide 7 by 49 or vice versa.
Is there a possibility to do that? I tried $project and $divide but had no luck.
Any help would be really appreciated.
Thank you,
From your question, it looks like you are assuming result count to be 2 only. In that case I can assume users.r can have only 2 values(apart from null).
The simplest thing I suggest is to do this arithmetic via javascript(if you're using it in mongo console) or in case of using it in progam, use the language you're using to access mongo) e.g.
var results = db.collection.aggregate([theAggregatePipelineQuery]).toArray();
print(results[0].count/results[1].count);
EDIT: I am sharing an alternative to above approach because OP commented about the constraint of not using javascript code and the need to be done only via query. Here it is
([
{ /**your existing aggregation stages that results in two rows as described in the question with a count field **/ },
{ $group: {"_id": 1, firstCount: {$first: "$count"}, lastCount: {$last: "$count"}
},
{ $project: { finalResult: { $divide: ['$firstCount','$lastCount']} } }
])
//The returned document has your answer under `finalResult` field
This question already has answers here:
MongoDb query condition on comparing 2 fields
(4 answers)
Closed 4 years ago.
I'm trying to query a huge mongo collection which have around 50 + Million records. In the mongo query , I only need few fields. Object ID and MD5 which is present in the document. For that , I did
Query :
db.getCollection('experimental_engine').find({},{"md5":1,"_id":1})
Result :
/* 1 */
{
"_id" : "5cee41f2ca4e0ebf567ffd1be5cdaf1f",
"md5" : "1d813cb29082b13efe572e8088f006dd"
}
/* 2 */
{
"_id" : "fcd79aac0d5c5ebdfd0fa389368ab6f3",
"md5" : "13a1a6cd5c8f1c5eaf3d409f4d809889"
}
/* 3 */
{
"_id" : "2a0b42d01892bd9b7368d045a4c7862c",
"md5" : "2a0b42d01892bd9b7368d045a4c7862c"
}
................
Now , i wanted to match both "_id" and "md5" and get only matching values ( _id = md5 ) .
Do mongo command support match values for two keys ?
Any suggestion please ?
You can use $expr which allows the use of aggregation expressions within the query language.
db.collection.find({ "$expr": { "$eq": [ "$_id" , "$md5" ] } })
or with aggregation
db.collection.aggregate([
{ "$match": { "$expr": { "$eq": [ "$_id" , "$md5" ] } } }
])
This question already has answers here:
Mongo field A greater than field B
(4 answers)
Closed 5 years ago.
I want to get records of a MongoDB collection that sticks to this condition: fieldA > fieldB + someNaturalValue. This is what I tried so far:
db.getCollection('collection').find({
$where: function() {
return this.fieldA > this.fieldB + 10000}
});
// or
db.getCollection('collection').aggregate([
{ "$project" : {
"sum" : {"$add" : ["$fieldB", 10000]}
}
},
{ "$match" : {
"sum" : {"$lte" : "$fieldA"}
}
}
]);
The issue I face here is the extra value that I need to add in the condition to one of the fields. Those are not working, that value is not taken into account. What I am missing? I appreciate any kind of help.
Sample Data
db.collection.insert({fieldA : 21000, fieldB : 10000}); //1 ok
db.collection.insert({fieldA : 15000, fieldB : 8000}); //2 nok
db.collection.insert({fieldA : 24000, fieldB : 22000}); //3 nok
db.collection.insert({fieldA : 22000, fieldB : 1000}); //4 ok
Adjusted code from the duplicated question:
db.collection.aggregate([
{$project: {
cmp_value: {$cmp: ['$fieldA', {$add: ['$fieldB', 10000]}]},
obj: '$$ROOT'
}},
{$match: {cmp_value: {$gt: 0}}},
{ $replaceRoot: { newRoot: '$obj' } }
])
$where should be avoided where possible. Documentation is quite clear about it:
The $where provides greater flexibility, but requires that the database processes the JavaScript expression or function for each document in the collection
This question already has answers here:
Query for documents where array size is greater than 1
(14 answers)
Closed 7 years ago.
Example document:
{
"aliases" : {
"name" : [
"Brinton McKay",
"Dr. Theopolis",
"Galactic Spiral Sound",
"Highrise",
"Memory Boy",
"Semblance Factor",
"Spy (2)",
"Three O'Clock High"]}
}
How i can count the number of "name" under "aliases"?
I would like to print all _id who which contains more than 3 aliases.
any help would be appreciated.
Please check the below query :
db.collection.find({ $where : function()
{ return Object.keys(this.aliases.name).length > 3 } });
OR
db.collection.aggregate([
{$project : { _id :1 , numb : {$size : "$aliases.name"} }
},
{$match : { numb :{$gt : 3 }}
}
]);
PS : you can see the documentation in below link :
http://docs.mongodb.org/manual/reference/operator/query/where/
I have a document with sub-document which looks something like:
{
"name" : "some name1"
"like" : [
{ "date" : ISODate("2012-11-30T19:00:00Z") },
{ "date" : ISODate("2012-12-02T19:00:00Z") },
{ "date" : ISODate("2012-12-01T19:00:00Z") },
{ "date" : ISODate("2012-12-03T19:00:00Z") }
]
}
Is it possible to fetch documents "most liked" (average value for the last 7 days) and sort by the count?
There are a few different ways to solve this problem. The solution I will focus on uses mongodb's aggregation framework. First, here is an aggregation pipeline that will solve your problem, following it will be an explanation/breakdown of what is happening in the command.
db.testagg.aggregate(
{ $unwind : '$likes' },
{ $group : { _id : '$_id', numlikes : { $sum : 1 }}},
{ $sort : { 'numlikes' : 1}})
This pipeline has 3 main commands:
1) Unwind: this splits up the 'likes' field so that there is 1 'like' element per document
2) Group: this regroups the document using the _id field, incrementing the numLikes field for every document it finds. This will cause numLikes to be filled with a number equal to the number of elements that were in "likes" before
3) Sort: Finally, we sort the return values in ascending order based on numLikes. In a test I ran the output of this command is:
{"result" : [
{
"_id" : 1,
"numlikes" : 1
},
{
"_id" : 2,
"numlikes" : 2
},
{
"_id" : 3,
"numlikes" : 3
},
{
"_id" : 4,
"numlikes" : 4
}....
This is for data inserted via:
for (var i=0; i < 100; i++) {
db.testagg.insert({_id : i})
for (var j=0; j < i; j++) {
db.testagg.update({_id : i}, {'$push' : {'likes' : j}})
}
}
Note that this does not completely answer your question as it avoids the issue of picking the date range, but it should hopefully get you started and moving in the right direction.
Of course, there are other ways to solve this problem. One solution might be to just do all of the sorting and manipulations client-side. This is just one method for getting the information you desire.
EDIT: If you find this somewhat tedious, there is a ticket to add a $size operator to the aggregation framework, I invite you to watch and potentially upvote it to try and speed to addition of this new operator if you are interested.
https://jira.mongodb.org/browse/SERVER-4899
A better solution would be to keep a count field that will record how many likes for this document. While you can use aggregation to do this, the performance will likely be not very good. Having a index on the count field will make read operation fast, and you can use atomic operation to increment the counter when inserting new likes.
You can use this simplify the above aggregation query by the following from mongodb v3.4 onwards:
> db.test.aggregate([
{ $unwind: "$like" },
{ $sortByCount: "$_id" }
]).pretty()
{ "_id" : ObjectId("5864edbfa4d3847e80147698"), "count" : 4 }
Also as #ACE said you can now use $size within a projection instead:
db.test.aggregate([
{ $project: { count: { $size : "$like" } } }
]);
{ "_id" : ObjectId("5864edbfa4d3847e80147698"), "count" : 4 }