Mongo Db query to get distinct records - mongodb

Question

I have below collections in DB around 1 million records. Hpw to get distinct eventID and eventName
from the collections in D for any particular date like 29-07-2020?
{
"_id" : 1814099,
"eventId" : "LAS012",
"eventName" : "CustomerTab",
"timeStamp" : ISODate("2018-12-31T20:09:09.820Z"),
"eventMethod" : "click",
"resourceName" : "CustomerTab",
"targetType" : "",
"resourseUrl" : "",
"operationName" : "",
"functionStatus" : "",
"results" : "",
"pageId" : "CustomerPage",
"ban" : "290824901",
"jobId" : "87377713",
"wrid" : "87377713",
"jobType" : "IBJ7FXXS",
"Uid" : "sc343x",
"techRegion" : "W",
"mgmtReportingFunction" : "N",
"recordPublishIndicator" : "Y",
"__v" : 0
}

Answer 1

You can use distinct, for example to fetch unique eventID:
let eventIds = await db.collection.distinct('eventID', {
"timeStamp": {
$gte: ISODate("2018-12-30T00:00:00.000Z"),
$lt: ISODate("2018-12-31T00:00:00.000Z")
}
})
If you want to retrieve both fields at the same time you'll have to use an aggregation:
db.collection.aggregate([
{
$match: {
"timeStamp": {
$gte: ISODate("2018-12-30T00:00:00.000Z"),
$lt: ISODate("2018-12-31T00:00:00.000Z")
}
}
},
{
$facet: {
eventIds: [
{
$group: {
_id: "$eventID"
}
}
],
eventName: [
{
$group: {
_id: "$eventName"
}
}
]
}
}
])
And if eventID and eventName are linked to one another:
db.collection.aggregate([
{
$match: {
"timeStamp": {
$gte: ISODate("2018-12-30T00:00:00.000Z"),
$lt: ISODate("2018-12-31T00:00:00.000Z")
}
}
},
{
$group: {
_id: {eventID: "$eventID", eventName: "$eventName"}
}
}
])