mongodb how to get max value from collections

Question

I have a mongodb collection like   db kids find     results        name  tom   age 10        name  alice   age 12                I need a query to get MAX  age  from this collection like in SQL  SELECT MAX age  FROM kids WHERE 1

User · Answer

The performance of the suggested answer is fine. According to the MongoDB documentation:

When a $sort immediately precedes a $limit, the optimizer can coalesce the $limit into the $sort. This allows the sort operation to only maintain the top n results as it progresses, where n is the specified limit, and MongoDB only needs to store n items in memory.

Changed in version 4.0.

So in the case of

db.collection.find().sort({age:-1}).limit(1)

we get only the highest element WITHOUT sorting the collection because of the mentioned optimization.

User · Answer

you can use group and max  db getCollection  kids   aggregate                  group                 id  null              maxQuantity    max   quot  age quot

User · Answer

what about using aggregate framework   db collection aggregate    group      id  null  max     max     age

User · Answer

You can also achieve this through aggregate pipeline   db collection aggregate    sort  age -1      limit 1

User · Answer

As one of comments   db collection find   sort  age -1   limit 1     for MAX db collection find   sort  age  1   limit 1     for MIN   it s completely usable but i m not sure about performance

User · Answer

For max value  we can write sql query as   select age from table name order by age desc limit 1   same way we can write in mongodb too   db getCollection  collection name   find   sort   age    -1   limit 1     max age db getCollection  collection name   find   sort   age    1   limit 1     min age

User · Answer

Folks you can see what the optimizer is doing by running a plan  The generic format of looking into a plan is from the MongoDB documentation   i e  Cursor plan    If you really want to dig deeper you can do a cursor plan true  for more details  Having said that if you have an index  your db col find   sort   quot field quot  -1   limit 1  will read one index entry - even if the index is default ascending and you wanted the max entry and one value from the collection  In other words the suggestions from  yogesh is correct  Thanks - Sumit

User · Answer

db collection findOne   sort  age -1     get Max without need for limit 1

User · Answer

Simple Explanation   if you have mongo query Response something like below - and you want only highest value from Array-    Date         id    57ee5a708e117c754915a2a2      TotalWishs   3     Events          57f805c866bf62f12edb8024          wish          Cosmic Eldorado  Mountain Bikes  26-inch  Grey White         Asics Men s Gel-Nimbus 18 Black  Snow and Fiery Red Running Shoes - 10 UK India  45 EU   11 US         Suunto Digital Black Dial Unisex Watch - SS018734000          Date          2017-02-13T00 00 00 000Z        2017-03-05T00 00 00 000Z          UserDetails                  createdAt    2016-09-30T12 28 32 773Z          jeenesFriends              57edf8a96ad8f6ff453a384a            57ee516c8e117c754915a26b            58a1644b6c91d2af783770b0            57ef4631b97d81824cf54795                  userImage    user profile Male png          email    roopak small-screen com          fullName    Roopak Kapoor                      Then you have add       Latest Wish CreatedDate     max    Date      somthing like below-                       project      id  1                               TotalWishs   1                                 wish 1                                  Events 1                                  Wish CreatedDate 1                                 Latest Wish CreatedDate     max    Date                                                    And Final Query Response will be below        id    57ee5a708e117c754915a2a2      TotalWishs   3     Events          57f805c866bf62f12edb8024          wish          Cosmic Eldorado  Mountain Bikes  26-inch  Grey White         Asics Men s Gel-Nimbus 18 Black  Snow and Fiery Red Running Shoes - 10 UK India  45 EU   11 US         Suunto Digital Black Dial Unisex Watch - SS018734000          Wish CreatedDate          2017-03-05T00 00 00 000Z        2017-02-13T00 00 00 000Z          UserDetails                  createdAt    2016-09-30T12 28 32 773Z          jeenesFriends              57edf8a96ad8f6ff453a384a            57ee516c8e117c754915a26b            58a1644b6c91d2af783770b0            57ef4631b97d81824cf54795                  userImage    user profile Male png          email    roopak small-screen com          fullName    Roopak Kapoor                Latest Wish CreatedDate    2017-03-05T00 00 00 000Z

[mongodb] mongodb how to get max value from collections

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