Mongoose limit/offset and count query
There is a library that will do all of this for you, check out mongoose-paginate-v2
I suggest you to use 2 queries:
db.collection.count()
will return total number of items. This value is stored somewhere in Mongo and it is not calculated.db.collection.find().skip(20).limit(10)
here I assume you could use a sort by some field, so do not forget to add an index on this field. This query will be fast too.
I think that you shouldn't query all items and than perform skip and take, cause later when you have big data you will have problems with data transferring and processing.
db.collection_name.aggregate([
{ '$match' : { } },
{ '$sort' : { '_id' : -1 } },
{ '$facet' : {
metadata: [ { $count: "total" } ],
data: [ { $skip: 1 }, { $limit: 10 },{ '$project' : {"_id":0} } ] // add projection here wish you re-shape the docs
} }
] )
Instead of using two queries to find the total count and skip the matched record.
$facet is the best and optimized way.
- Match the record
- Find total_count
- skip the record
- And also can reshape data according to our needs in the query.
Instead of using 2 separate queries, you can use aggregate()
in a single query:
Aggregate "$facet" can be fetch more quickly, the Total Count and the Data with skip & limit
db.collection.aggregate([
//{$sort: {...}}
//{$match:{...}}
{$facet:{
"stage1" : [ {"$group": {_id:null, count:{$sum:1}}} ],
"stage2" : [ { "$skip": 0}, {"$limit": 2} ]
}},
{$unwind: "$stage1"},
//output projection
{$project:{
count: "$stage1.count",
data: "$stage2"
}}
]);
output as follows:-
[{
count: 50,
data: [
{...},
{...}
]
}]
Also, have a look at https://docs.mongodb.com/manual/reference/operator/aggregation/facet/