인덱스 (Index)

Functions for Index

• Creates an index on this collection.

create_index([(‘index_name’, order)]) 
e.g.) my_collection.create_index([(‘address’, 1)]) 

• Get information on collections’s indexes

index_information()
e.g.) my_collection.index_information()

• Drops the specified index on this collection

drop_index ([(‘index_name’, order)])
my_collection.drop_index([(‘address’, 1)]) 

• To drop all indexes on this collection, use drop_indexes()

Compound Index

• Create indexes on more than one field.

my_collection.create_index([
(‘name’, pymongo.DESCENDING),
(‘address’, pymongo.ASCENDING)])
e.g.)
my_collection.create_index([(‘name’, -1), (‘address’, 1)])

PyMongo에서 가독성을 위해 값을 제공하고 있다. 아래는 같은 뜻으로 이해하면 되겠다.

pymongo.ASCENDING = 1, pymongo.DESCENDING = -1

Indexing on Embedded Document

• Indexes can be created on keys in embedded documents.

collection.create_index([('parent.child', pymongo.ASCENDING)])

• Indexing to Array

collection.create_index([('items.name', pymongo.DESCENDING)])

Unique & Sparse Index

• Unique indexes guarantee that each value will appear at most once in the index

collection.create_index([('key_1', 1)], unique=True)

• Sparse indexes only contain entries for documents that have the indexed field skipping documents without it.

collection.create_index([('key_2', 1)], sparse=True)

• Unique & Sparse

collection.create_index([(key_3', 1)], unique=True, sparse=True)

Hint

• To override MongoDB’s default index selection and query optimization process.

collection.find().sort([('key_4', 1)]).hint([('key_4', 1)])

Geospatial Index

• Type

  • pymongo.GEO2D ==> 2d

  • pymongo.GEOSPHERE ==> 2dsphere

collection.create_index( [ (‘field’, TYPE) ] ) # Create Inde
collection.drop_index( [ (‘field’, TYPE) ] )  # Drop Index

• Example

from pymongo import MongoClient, GEOSPHERE
client = MongoClient()
db = client.geo
col = db.states
col.create_index([("loc", GEOSPHERE)])

Text Index

• Create a text index on one field

collection.create_index( 
[ ( 'field', pymongo.TEXT ) ] )

• Create text indexes on multiple fields

collection.create_index( 
[ ( 'field_1', pymongo.TEXT ), 
( 'field_2', pymongo.TEXT ) ] )

• Specify the weight of an indexed

collection.create_index( 
[ ( 'field_1', pymongo.TEXT ), 
( 'field_2', pymongo.TEXT ) ], 
weights={ 'field_1' : 3, 'field_2' : 2 } )