OPTIONS

cursor.min()

Definition

cursor.min()

Specifies the inclusive lower bound for a specific index in order to constrain the results of find(). min() provides a way to specify lower bounds on compound key indexes.

The min() has the following parameter:

Parameter Type Description
indexBounds document The inclusive lower bound for the index keys.

The indexBounds parameter has the following prototype form:

{ field1: <min value>, field2: <min value2>, fieldN:<min valueN> }

The fields correspond to all the keys of a particular index in order. You can explicitly specify the particular index with the hint() method. Otherwise, MongoDB selects the index using the fields in the indexBounds; however, if multiple indexes exist on same fields with different sort orders, the selection of the index may be ambiguous.

See also

max().

Note

min() is a shell wrapper around the query modifier $min.

Behaviors

  • Because min() requires an index on a field, and forces the query to use this index, you may prefer the $gte operator for the query if possible. Consider the following example:

    db.products.find( { _id: 7 } ).min( { price: 1.39 } )
    

    The query will use the index on the price field, even if the index on _id may be better.

  • min() exists primarily to support the mongos process.

  • If you use min() with max() to specify a range, the index bounds specified in min() and max() must both refer to the keys of the same index.

Example

This example assumes a collection named products that holds the following documents:

{ "_id" : 6, "item" : "apple", "type" : "cortland", "price" : 1.29 }
{ "_id" : 2, "item" : "apple", "type" : "fuji", "price" : 1.99 }
{ "_id" : 1, "item" : "apple", "type" : "honey crisp", "price" : 1.99 }
{ "_id" : 3, "item" : "apple", "type" : "jonagold", "price" : 1.29 }
{ "_id" : 4, "item" : "apple", "type" : "jonathan", "price" : 1.29 }
{ "_id" : 5, "item" : "apple", "type" : "mcintosh", "price" : 1.29 }
{ "_id" : 7, "item" : "orange", "type" : "cara cara", "price" : 2.99 }
{ "_id" : 10, "item" : "orange", "type" : "navel", "price" : 1.39 }
{ "_id" : 9, "item" : "orange", "type" : "satsuma", "price" : 1.99 }
{ "_id" : 8, "item" : "orange", "type" : "valencia", "price" : 0.99 }

The collection has the following indexes:

{ "_id" : 1 }
{ "item" : 1, "type" : 1 }
{ "item" : 1, "type" : -1 }
{ "price" : 1 }
  • Using the ordering of the { item: 1, type: 1 } index, min() limits the query to the documents that are at or above the index key bound of item equal to apple and type equal to jonagold, as in the following:

    db.products.find().min( { item: 'apple', type: 'jonagold' } ).hint( { item: 1, type: 1 } )
    

    The query returns the following documents:

    { "_id" : 3, "item" : "apple", "type" : "jonagold", "price" : 1.29 }
    { "_id" : 4, "item" : "apple", "type" : "jonathan", "price" : 1.29 }
    { "_id" : 5, "item" : "apple", "type" : "mcintosh", "price" : 1.29 }
    { "_id" : 7, "item" : "orange", "type" : "cara cara", "price" : 2.99 }
    { "_id" : 10, "item" : "orange", "type" : "navel", "price" : 1.39 }
    { "_id" : 9, "item" : "orange", "type" : "satsuma", "price" : 1.99 }
    { "_id" : 8, "item" : "orange", "type" : "valencia", "price" : 0.99 }
    

    If the query did not explicitly specify the index with the hint() method, it is ambiguous as to whether mongod would select the { item: 1, type: 1 } index ordering or the { item: 1, type: -1 } index ordering.

  • Using the ordering of the index { price: 1 }, min() limits the query to the documents that are at or above the index key bound of price equal to 1.39 and max() limits the query to the documents that are below the index key bound of price equal to 1.99:

    db.products.find().min( { price: 1.39 } ).max( { price: 1.99 } ).hint( { price: 1 } )
    

    The query returns the following documents:

    { "_id" : 6, "item" : "apple", "type" : "cortland", "price" : 1.29 }
    { "_id" : 4, "item" : "apple", "type" : "jonathan", "price" : 1.29 }
    { "_id" : 5, "item" : "apple", "type" : "mcintosh", "price" : 1.29 }
    { "_id" : 3, "item" : "apple", "type" : "jonagold", "price" : 1.29 }
    { "_id" : 10, "item" : "orange", "type" : "navel", "price" : 1.39 }