problem while using sort,skip and limit together

[Sajal Pal]

Suppose I have 30 records in a collection, Now I want to fetch 1st 10 records then 2nd 10 then 3rd 10 records. by running the query each time with skip value and Limit value.

Query-1(To fetch 1st 10 records)

db.AutoVertical.aggregate([

{$project : {"DealerName" : "$DealerName", "DealerPhone" : "$DealerPhone",  "DealerAddress" : "$DealerAddress"}},

{$sort :

   {'DealerName': 1}

 },

 {$limit : 10 },

 {$skip : 0} 

])

Query-2(To fetch 2nd 10 records)

db.AutoVertical.aggregate([

{$project : {"DealerName" : "$DealerName", "DealerPhone" : "$DealerPhone",  "DealerAddress" : "$DealerAddress"}},

{$sort :

   {'DealerName': 1}

 },

 {$limit : 10 },

 {$skip : 10} 

])

Query-3(To fetch 3rd 10 records)

db.AutoVertical.aggregate([

{$project : {"DealerName" : "$DealerName", "DealerPhone" : "$DealerPhone",  "DealerAddress" : "$DealerAddress"}},

{$sort :

   {'DealerName': 1}

 },

 {$limit : 10 },

 {$skip : 20} 

])

Now I am facing the issue is that sorting is not working properly. When I run the 1st query I am getting(a,b,c,d....) and then when I am running the 2nd query I am getting (a,b,x,y....).The problem is that I am getting a,b in both the result set.

can any one help me 

[Asya Kamsky]

You're doing something strange here - you have $skip after $limit?

That means you are always getting the first 10 records going into
$skip. {$limit:10} followed by {$skip:10} will alway return nothing.

Order matters! At least in aggregation where stages are processed in order.

Asya

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--
Asya Kamsky
Lead Product Manager
MongoDB
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