Create mongodb index based on gt and lt - database

Question

I have Collection has many documents which called "products",
I want to improve performance by creating an index for it.
The problem is IDK how the index works, So IDK index will helpful or not.
My most frequently used query is about fields "storeId" and "salesDates"
storeId is just string so I think it good to create an index,
But the tricky one is salesDates, salesDates is Object has two fields from and to like this
product {
...someFields,
storeId: string,
salesDate {
from: Date time Number
to: Date time Number
}
}
My query is based on $gt $lt for example
product.find({
storeId: "blah",
salesDate.from : {$gt: 1423151234, $lt: 15123123123 }
})
OR
product.find({
storeId: "blah",
salesDate.from: {$gt: 1423151234},
salesDate.to: {$lt: 15123123123 }
})
What is the proper index for this case?

Answer 1

For your specific use case, I would recommend you to create an index only on
the from key and use $ge and $le in your find query.
The reason is that the lesser the number of keys you are indexing (in cases where the multiple key queries can be avoided), the better it is.
make sure that you follow the below order for both the indexing and find operation.
Index Command and Order:
db,product.createIndex({
"storeId": 1,
"salesDate.from": -1, // Change `-1` to `1` if you want to ISODate key to be indexed in Ascending order
})
Find Command:
db,product.find({
"storeId": "blah",
"salesDate.from": {$gt: 1423151234, $lt: 15123123123 },
})