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Azure Cosmos DB is a globally distributed, multi-model database service that supports document, key-value, wide-column, and graph databases.
Use the Azure Cosmos DB SQL API SDK for Python to manage databases and the JSON documents they contain in this NoSQL database service.
- Create Cosmos DB databases and modify their settings
- Create and modify containers to store collections of JSON documents
- Create, read, update, and delete the items (JSON documents) in your containers
- Query the documents in your database using SQL-like syntax
Looking for source code or API reference?
Please see the latest version of the Azure Cosmos DB Python SDK for SQL API
- Azure subscription - Create a free account
- Azure Cosmos DB account - SQL API
- Python 2.7 or 3.5.3+
If you need a Cosmos DB SQL API account, you can create one with this Azure CLI command:
az cosmosdb create --resource-group <resource-group-name> --name <cosmos-account-name>
pip install azure-cosmos
Although not required, you can keep your your base system and Azure SDK environments isolated from one another if you use a virtual environment. Execute the following commands to configure and then enter a virtual environment with venv:
python3 -m venv azure-cosmosdb-sdk-environment
source azure-cosmosdb-sdk-environment/bin/activate
Interaction with Cosmos DB starts with an instance of the CosmosClient class. You need an account, its URI, and one of its account keys to instantiate the client object.
Use the Azure CLI snippet below to populate two environment variables with the database account URI and its primary master key (you can also find these values in the Azure portal). The snippet is formatted for the Bash shell.
RES_GROUP=<resource-group-name>
ACCT_NAME=<cosmos-db-account-name>
export ACCOUNT_URI=$(az cosmosdb show --resource-group $RES_GROUP --name $ACCT_NAME --query documentEndpoint --output tsv)
export ACCOUNT_KEY=$(az cosmosdb keys list --resource-group $RES_GROUP --name $ACCT_NAME --query primaryMasterKey --output tsv)
Once you've populated the ACCOUNT_URI
and ACCOUNT_KEY
environment variables, you can create the CosmosClient.
import azure.cosmos.cosmos_client as cosmos_client
import azure.cosmos.errors as errors
import azure.cosmos.http_constants as http_constants
import os
url = os.environ['ACCOUNT_URI']
key = os.environ['ACCOUNT_KEY']
client = cosmos_client.CosmosClient(url, {'masterKey': key})
When you create a Cosmos DB Database Account, you specify the API you'd like to use when interacting with its documents: SQL, MongoDB, Gremlin, Cassandra, or Azure Table.
This SDK is used to interact with an SQL API database account.
Once you've initialized a CosmosClient, you can interact with the primary resource types in Cosmos DB:
-
Database: A Cosmos DB account can contain multiple databases. A database may contain a number of containers.
-
Container: A container is a collection of JSON documents. You create (insert), read, update, and delete items in a container.
-
Item: An Item is the dictionary-like representation of a JSON document stored in a container. Each Item you add to a container must include an
id
key with a value that uniquely identifies the item within the container.
For more information about these resources, see Working with Azure Cosmos databases, containers and items.
The following sections provide several code snippets covering some of the most common Cosmos DB tasks, including:
- Create a database
- Create a container
- Replace throughput for a container
- Get an existing container
- Insert data
- Delete data
- Query the database
- Modify container properties
After authenticating your CosmosClient, you can work with any resource in the account. You can use CosmosClient.CreateDatabase to create a database.
database_name = 'testDatabase'
try:
database = client.CreateDatabase({'id': database_name})
except errors.HTTPFailure:
database = client.ReadDatabase("dbs/" + database_name)
This example creates a container with 400 RU/s as the throughput, using CosmosClient.CreateContainer. If a container with the same name already exists in the database (generating a 409 Conflict
error), the existing container is obtained instead.
import azure.cosmos.documents as documents
container_definition = {
'id': 'products',
'partitionKey': {
'paths': ['/productName'],
'kind': documents.PartitionKind.Hash
}
}
try:
container = client.CreateContainer(
"dbs/" + database['id'], container_definition, {'offerThroughput': 400})
except errors.HTTPFailure as e:
if e.status_code == http_constants.StatusCodes.CONFLICT:
container = client.ReadContainer(
"dbs/" + database['id'] + "/colls/" + container_definition['id'])
else:
raise e
A single offer object exists per container. This object contains information regarding the container's throughput. This example retrieves the offer object using CosmosClient.QueryOffers, and modifies the offer object and replaces the throughput for the container using CosmosClient.ReplaceOffer.
# Get the offer for the container
offers = list(client.QueryOffers(
"Select * from root r where r.offerResourceId='" + container['_rid'] + "'"))
offer = offers[0]
print("current throughput for " + container['id'] + ": " +
str(offer['content']['offerThroughput']))
# Replace the offer with a new throughput
offer['content']['offerThroughput'] = 1000
client.ReplaceOffer(offer['_self'], offer)
print("new throughput for " + container['id'] + ": " +
str(offer['content']['offerThroughput']))
Retrieve an existing container from the database using CosmosClient.ReadContainer:
database_id = 'testDatabase'
container_id = 'products'
container = client.ReadContainer("dbs/" + database_id + "/colls/" + container_id)
To insert items into a container, pass a dictionary containing your data to CosmosClient.UpsertItem. Each item you add to a container must include an id
key with a value that uniquely identifies the item within the container.
This example inserts several items into the container, each with a unique id
:
for i in range(1, 10):
client.UpsertItem(
"dbs/" + database_id + "/colls/" + container_id,
{
'id': 'item{0}'.format(i),
'productName': 'Widget',
'productModel': 'Model {0}'.format(i)
}
)
To delete items from a container, use CosmosClient.DeleteItem. The SQL API in Cosmos DB does not support the SQL DELETE
statement.
for item in client.QueryItems(
"dbs/" + database_id + "/colls/" + container_id,
'SELECT * FROM products p WHERE p.productModel = "DISCONTINUED"',
{'enableCrossPartitionQuery': True}):
client.DeleteItem(
"dbs/" + database_id + "/colls/" + container_id + "/docs/" + item['id'],
{'partitionKey': 'Pager'})
A Cosmos DB SQL API database supports querying the items in a container with CosmosClient.QueryItems using SQL-like syntax.
This example queries a container for items with a specific id
:
database = client.get_database_client(database_name)
container = database.get_container_client(container_name)
# Enumerate the returned items
import json
for item in client.QueryItems(
"dbs/" + database_id + "/colls/" + container_id,
'SELECT * FROM ' + container_id + ' r WHERE r.id="item3"',
{'enableCrossPartitionQuery': True}):
print(json.dumps(item, indent=True))
NOTE: Although you can specify any value for the container name in the
FROM
clause, we recommend you use the container name for consistency.
Perform parameterized queries by passing a dictionary containing the parameters and their values to CosmosClient.QueryItems:
discontinued_items = client.QueryItems(
"dbs/" + database_id + "/colls/" + container_id,
{
'query': 'SELECT * FROM root r WHERE r.id=@id',
'parameters': [
{'name': '@id', 'value': 'item3'}
]
},
{'enableCrossPartitionQuery': True})
for item in discontinued_items:
print(json.dumps(item, indent=True))
For more information on querying Cosmos DB databases using the SQL API, see Query Azure Cosmos DB data with SQL queries.
Certain properties of an existing container can be modified. This example sets the default time to live (TTL) for items in the container to 10 seconds:
container = client.ReadContainer("dbs/" + database_id + "/colls/" + container_id)
container['defaultTtl'] = 10
modified_container = client.ReplaceContainer(
"dbs/" + database_id + "/colls/" + container_id, container)
# Display the new TTL setting for the container
print(json.dumps(modified_container['defaultTtl']))
For more information on TTL, see Time to Live for Azure Cosmos DB data.
When you interact with Cosmos DB using the Python SDK, errors returned by the service correspond to the same HTTP status codes returned for REST API requests:
HTTP Status Codes for Azure Cosmos DB
For example, if you try to create a container using an ID (name) that's already in use in your Cosmos DB database, a 409
error is returned, indicating the conflict. In the following snippet, the error is handled gracefully by catching the exception and displaying additional information about the error.
try:
container = client.CreateContainer("dbs/" + database['id'], container_definition)
except errors.HTTPFailure as e:
if e.status_code == http_constants.StatusCodes.CONFLICT:
print("""Error creating container
HTTP status code 409: The ID (name) provided for the container is already in use.
The container name must be unique within the database.""")
else:
raise e
For more extensive documentation on the Cosmos DB service, see the Azure Cosmos DB documentation on docs.microsoft.com.
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