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Indexing

The driver provides the ability to create, drop and view indexes on a collection.

Creating Indexes

Indexes can be created one at a time, or several can be created in a single operation. When creating multiple indexes on MongoDB 3.0 and later, the indexes are created in parallel. On earlier versions they are created in order.

To create a single index, use create_one.

client = Mongo::Client.new([ '127.0.0.1:27017' ], :database => 'music')
client[:bands].indexes.create_one( { :name => 1 }, unique: true )

To create multiple indexes, use create_many. Note that when creating many, the index keys must be passed as a key value in the provided spec. This is due to the fact that options can be different for each index being created.

client = Mongo::Client.new([ '127.0.0.1:27017' ], :database => 'music')
client[:bands].indexes.create_many([
  { :key => { name: 1 }, unique: true },
  { :key => { label: -1 } }
])

The following is a full list of the available options that can be added when creating indexes.

Option Description
:background Either true or false. Tells the index to be created in the background.
:expire_after Number of seconds to expire documents in the collection after.
:name The name of the index.
:sparse Whether the index should be sparse or not, either true or false.
:storage_engine The name of the storage engine for this particular index.
:version The index format version to use.
:default_language The default language of text indexes.
:language_override The field name to use when overriding the default language.
:text_version The version format for text index storage.
:weights A document specifying fields and weights in text search.
:sphere_version The 2d sphere index version.
:bits Sets the maximum boundary for latitude and longitude in the 2d index.
:max Maximum boundary for latitude and longitude in the 2d index.
:min Minimum boundary for latitude and longitude in the 2d index.
:bucket_size The number of units within which to group the location values in a geo haystack index.
:partial_filter_expression A filter for a partial index.

Dropping Indexes

To drop an index, call dropOne or dropAll.

client = Mongo::Client.new([ '127.0.0.1:27017' ], :database => 'music')

client[:bands].indexes.drop_one( 'name_1' ) # Drops the name_1 index.
client[:bands].indexes.drop_all # Drops all indexes in the collection.

Listing Indexes

client = Mongo::Client.new([ '127.0.0.1:27017' ], :database => 'music')

client[:bands].indexes.each do |index|
  p index
end
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