Scenario: Consider, I have the following collection in the MongoDB:
{
"_id" : "CustomeID_3723",
"IsActive" : "Y",
"CreatedDateTime" : "2013-06-06T14:35:00Z"
}
Now I want to know the count of the created document on the particular day (say on 2013-03-04)
So, I am trying to find the solution using aggregation framework.
Information:
So far I have the following query built:
collection.aggregate([
{ $group: {
_id: '$CreatedDateTime'
}
},
{ $group: {
count: { _id: null, $sum: 1 }
}
},
{ $project: {
_id: 0,
"count" :"$count"
}
}
])
Issue: Now considering above query, its giving me the count. But not based on only date! Its taking time as well into consideration for unique count.
Question: Considering the field has ISO date, Can any one tell me how to count the documents based on only date (i.e excluding time)?
Replace your two groups with
{$project:{day:{$dayOfMonth:'$createdDateTime'},month:{$month:'$createdDateTime'},year:{$year:'$createdDateTime'}}},
{$group:{_id:{day:'$day',month:'$month',year:'$year'}, count: {$sum:1}}}
You can read more about the date operators here: http://docs.mongodb.org/manual/reference/aggregation/#date-operators
Related
I am having a record set like below :
I need to write a query where foreach datatype of every parent I show the data type with highest date i.e
So far I am able to create two groups one on parent id & other on data type but i am unable to understand how to get record with max date.
Below is my query :
db.getCollection('Maintenance').aggregate( [{ $group :
{ _id :{ parentName: "$ParentID" , maintainancename : "$DataType" }}},
{ $group : {
_id : "$_id.parentName",
maintainancename: {
$push: {
term:"$_id.DataType"
}
}
}
}] )
You don't have to $group twice, try below aggregation query :
db.collection.aggregate([
/** group on two fields `ParentID` & `Datatype`,
* which will leave docs with unique `ParentID + Datatype`
* & use `$max` to get max value on `Date` field in unique set of docs */
{
$group: {
_id: {
parentName: "$ParentID",
maintainancename: "$Datatype"
},
"Date": { $max: "$Date" }
}
}
])
Test : mongoplayground
Note : After group stage you can use $project or $addFieldsstages to transform fields the way you want.
I have a collection of 100 records.Each record have date field like below
"created_date" : ISODate("2018-11-20T00:00:00.000Z")
I want to update each record by removing the time like below
"created_date" : "2018-11-20"
How to write a query for this kind of update
You can remove the timestamp from the date using Aggregate Query and update collection using forEach function. It may take time but it will update the collection data as per your requirement. Here is Mongo aggregation query:
db.getCollection('demo').aggregate([
{
$addFields: {
DateinString: {
$dateToString: {
format: "%Y-%m-%d",
date: "$created_date"
}
}
}
}
]).forEach(function(myDoc){
db.getCollection("demo").update({
_id: myDoc._id
}, {
$set: {
"created_date": myDoc.DateinString
}
})
})
My schema implementation is influenced from this tutorial on official mongo site
{
_id: String,
data:[
{
point_1: Number,
ts: Date
}
]
}
This is basically schema designed for time series data and I store data for each hour per device in an array in a single document. I create _id field combining device id which is sending the data and time. For example if a device having id xyz1234 sends a data at 2018-09-11 12:30:00 then my _id field becomes xyz1234:2018091112.
I create new doc if the document for that hour for that device doesn't exist otherwise I just push my data to the data array.
client.db('iot')
.collection('iotdata')
.update({_id:id},{$push:{data:{point_1,ts:date}}},{upsert:true});
Now I am facing problem while doing aggregation. I am trying to get these types of values
Min point_1 value for many devices in last 24 hours by grouping on device id
Max point_1 value for many devices in last 24 hours by grouping on device id
Average point_1 for many devices in last 24 hours by grouping on device id
I thought this is very simple aggregation then I realized device id is not direct but mixed with time data so it's not so direct to group data by device id. How can I split the _id and group based on device id? I tried my level best to write the question as clearly as possible so please ask questions in comments if any part of the question is not clear.
You can start with $unwind on data to get single document per entry. Then you can get deviceId using $substr and $indexOfBytes operators. Then you can apply your filtering condition (last 24 hours) and use $group to get min, max and avg
db.col.aggregate([
{
$unwind: "$data"
},
{
$project: {
point_1: "$data.point_1",
deviceId: { $substr: [ "$_id", 0, { $indexOfBytes: [ "$_id", ":" ] } ] },
dateTime: "$data.ts"
}
},
{
$match: {
dateTime: { $gte: ISODate("2018-09-10T12:00:00Z") }
}
},
{
$group: {
_id: "$deviceId",
min: { $min: "$point_1" },
max: { $max: "$point_1" },
avg: { $avg: "$point_1" }
}
}
])
You can use below query in 3.6.
db.colname.aggregate([
{"$project":{
"deviceandtime":{"$split":["$_id", ":"]},
"minpoint":{"$min":"$data.point_1"},
"maxpoint":{"$min":"$data.point_1"},
"sumpoint":{"$sum":"$data.point_1"},
"count":{"$size":"$data.point_1"}
}},
{"$match":{"$expr":{"$gte":[{"$arrayElemAt":["$deviceandtime",1]},"2018-09-10 00:00:00"]}}},
{"$group":{
"_id":{"$arrayElemAt":["$deviceandtime",0]},
"minpoint":{"$min":"$minpoint"},
"maxpoint":{"$max":"$maxpoint"},
"sumpoint":{"$sum":"$sumpoint"},
"countpoint":{"$sum":"$count"}
}},
{"$project":{
"minpoint":1,
"maxpoint":1,
"avgpoint":{"$divide":["$sumpoint","$countpoint"]}
}}
])
I'm trying to minimize the number of database calls in an application.
Is it possible to complete these two queries in a single call?
system_0 = System.objects(platform_id=platform_id, type=0).count()
system_1 = System.objects(platform_id=platform_id, type=1).count()
I do not know what is mongoengine, but I think you will be capable of translating my mongo shell answer to what is appropriate for you. Yes, you can achieve it with aggregation. For example:
db.collection.aggregate([{
$match : { platform_id : ... }
}, {
$group: {
_id: "$type",
count: { $sum: 1 }
}
}]);
If you have more types than 0, 1, you can exclude them in $match as well.
I have a collection named 'sentences'. I would like a list of all the unique values of 'last_syls' where the number of entries containing that value of 'last_syls' is greater than 10.
A document in this collection looks like:
{ "_id" : ObjectId( "51dd9011cf2bee3a843f215a" ),
"last_syls" : "EY1D",
"last_word" : "maid"}
I've looked into db.sentences.distinct('last_syls'), but cannot figure out how to query based on the count for each of these distinct values.
You're going to want to use the aggregation framework:
db.sentences.aggregate([
{
$group: {
_id: "$last_syls",
count: { $sum: 1}
}
},
{
$match: {
count: { $gt: 10 }
}
}
])
This groups documents by their last_syls field with a count per group, then filters that result set to all results with a count greater than 10.