$sort (aggregation) in MongoDB

$sort is responsible for sorting input document and returns it to the pipeline. If you are aware of relational Databases like SQL server $sort work same as ORDER BY clause.

Syntax:

{ $sort: { <field1>: <sort order>, <field2>: <sort order> ... } }

$sort use to sort result in ascending or descending order according to particular field(s). For ascending and descending we used the following values.

• 1 for the ascending.
• -1 for descending

Example:

Suppose we have a collection named “myCollection “as below.

{ "uid" : 1, " Book  Title": "book1", "price" : 20, "quantity" : 1, "date" : ISODate("2016-08-05T07:00:00Z") } { "uid" : 2, " Book Title " : " book2", "price" : 10, "quantity" : 2, "date" : ISODate("2016-08-05T08:00:00Z") } { "uid" : 3, " Book Title " : " book3", "price" : 30, "quantity" : 4, "date" : ISODate("2016-08-17T10:00:00Z") } { "uid" : 4, " Book Title " : " book4", "price" : 10, "quantity" : 2, "date" : ISODate("2014-09-01T11:20:39.736Z") } { "uid" : 5, " Book Title " : " book5", "price" : 20, "quantity" : 6, "date" : ISODate("2014-09-04T20:23:13.331Z") }

Execute following query:

db.myCollection.aggregate(    [      { $sort : { quantity : -1 } }    ] )

Result: Above query returns documents as sorted by quantity descending. 

/* 1 */ {     "_id" : ObjectId("5767b6e21130fb71878298b2"),     "uid" : 5,     " Book Title " : " book5",     "price" : 20,     "quantity" : 6,     "date" : ISODate("2014-09-04T20:23:13.331Z") } /* 2 */ {     "_id" : ObjectId("5767b6e21130fb71878298b0"),     "uid" : 3,     " Book Title " : " book3",     "price" : 30,     "quantity" : 4,     "date" : ISODate("2016-08-17T10:00:00.000Z") } /* 3 */ {     "_id" : ObjectId("5767b6e21130fb71878298af"),     "uid" : 2,     " Book Title " : " book2",     "price" : 10,     "quantity" : 2,     "date" : ISODate("2016-08-05T08:00:00.000Z") } /* 4 */ {     "_id" : ObjectId("5767b6e21130fb71878298b1"),     "uid" : 4,     " Book Title " : " book4",     "price" : 10,     "quantity" : 2,     "date" : ISODate("2014-09-01T11:20:39.736Z") } /* 5 */ {     "_id" : ObjectId("5767b6e21130fb71878298ae"),     "uid" : 1,     " Book  Title" : "book1",     "price" : 20,     "quantity" : 1,     "date" : ISODate("2016-08-05T07:00:00.000Z") }

Same like above query we can apply ascending for the result.

db.myCollection.aggregate(    [      { $sort : { quantity : 1 } }    ] )

Result:

/* 1 */ {     "_id" : ObjectId("5767b6e21130fb71878298ae"),     "uid" : 1,     " Book  Title" : "book1",     "price" : 20,     "quantity" : 1,     "date" : ISODate("2016-08-05T07:00:00.000Z") } /* 2 */ {     "_id" : ObjectId("5767b6e21130fb71878298af"),     "uid" : 2,     " Book Title " : " book2",     "price" : 10,     "quantity" : 2,     "date" : ISODate("2016-08-05T08:00:00.000Z") } /* 3 */ {     "_id" : ObjectId("5767b6e21130fb71878298b1"),     "uid" : 4,     " Book Title " : " book4",     "price" : 10,     "quantity" : 2,     "date" : ISODate("2014-09-01T11:20:39.736Z") } /* 4 */ {     "_id" : ObjectId("5767b6e21130fb71878298b0"),     "uid" : 3,     " Book Title " : " book3",     "price" : 30,     "quantity" : 4,     "date" : ISODate("2016-08-17T10:00:00.000Z") } /* 5 */ {     "_id" : ObjectId("5767b6e21130fb71878298b2"),     "uid" : 5,     " Book Title " : " book5",     "price" : 20,     "quantity" : 6,     "date" : ISODate("2014-09-04T20:23:13.331Z") }

Note: The $sort stage has a limit of 100 megabytes of RAM.