I need some help: I want to optimize this query to be faster , it need to filter by events.eventType:"log" all docs with server:"strong" , but without separate unwind & filter stages , maybe somehow inside the $reduce stage to add $filter.
example single document:
{
server: "strong",
events: [
{
eventType: "log",
createdAt: "2022-01-23T10:26:11.214Z",
visitorInfo: {
visitorId: "JohnID"
}
}
current aggregation query:
db.collection.aggregate([
{
$match: {
server: "strong"
}
},
{
$project: {
total: {
$reduce: {
input: "$events",
initialValue: {
visitor: [],
uniquevisitor: []
},
in: {
visitor: {
$concatArrays: [
"$$value.visitor",
[
"$$this.visitorInfo.visitorId"
]
]
},
uniquevisitor: {
$cond: [
{
$in: [
"$$this.visitorInfo.visitorId",
"$$value.uniquevisitor"
]
},
"$$value.uniquevisitor",
{
$concatArrays: [
"$$value.uniquevisitor",
[
"$$this.visitorInfo.visitorId"
]
]
}
]
}
}
}
}
}
}
])
expected output , two lists with unique visitorId & list of all visitorId:
[
{
"total": {
"uniquevisitor": [
"JohnID"
],
"visitor": [
"JohnID",
"JohnID"
]
}
} ]
In the example query no filter is added for events.eventType:"log" , how can this be implemented without $unwind?
I am not sure this approach is more optimized than yours but might be this will help,
$filter to iterate loop of events and filter by eventType$let to declare a variable events and store the above filters resultvisitor by using dot notation $$events.visitorInfo.visitorIduniquevisitor by using dot notation $$events.visitorInfo.visitorId and $setUnion operatordb.collection.aggregate([
{ $match: { server: "strong" } },
{
$project: {
total: {
$let: {
vars: {
events: {
$filter: {
input: "$events",
cond: { $eq: ["$$this.eventType", "log"] }
}
}
},
in: {
visitor: "$$events.visitorInfo.visitorId",
uniquevisitor: {
$setUnion: "$$events.visitorInfo.visitorId"
}
}
}
}
}
}
])
Or similar approach without $let and two $project stages,
db.collection.aggregate([
{ $match: { server: "strong" } },
{
$project: {
events: {
$filter: {
input: "$events",
cond: { $eq: ["$$this.eventType", "log"] }
}
}
}
},
{
$project: {
total: {
visitor: "$events.visitorInfo.visitorId",
uniquevisitor: {
$setUnion: "$events.visitorInfo.visitorId"
}
}
}
}
])