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Unified Diff: third_party/gsutil/boto/docs/source/dynamodb_tut.rst

Issue 10199002: Upgrade gsutil to 3.4 (Closed) Base URL: https://dart.googlecode.com/svn/branches/bleeding_edge/dart
Patch Set: Addressed comments Created 8 years, 8 months ago
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Index: third_party/gsutil/boto/docs/source/dynamodb_tut.rst
diff --git a/third_party/gsutil/boto/docs/source/dynamodb_tut.rst b/third_party/gsutil/boto/docs/source/dynamodb_tut.rst
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+.. dynamodb_tut:
+
+============================================
+An Introduction to boto's DynamoDB interface
+============================================
+
+This tutorial focuses on the boto interface to AWS' DynamoDB_. This tutorial
+assumes that you have boto already downloaded and installed.
+
+.. _DynamoDB: http://aws.amazon.com/dynamodb/
+
+Creating a Connection
+---------------------
+
+The first step in accessing DynamoDB is to create a connection to the service.
+To do so, the most straight forward way is the following::
+
+ >>> import boto
+ >>> conn = boto.connect_dynamodb(
+ aws_access_key_id='<YOUR_AWS_KEY_ID>',
+ aws_secret_access_key='<YOUR_AWS_SECRET_KEY>')
+ >>> conn
+ <boto.dynamodb.layer2.Layer2 object at 0x3fb3090>
+
+Bear in mind that if you have your credentials in boto config in your home
+directory, the two keyword arguments in the call above are not needed. More
+details on configuration can be found in :doc:`boto_config_tut`.
+
+.. note:: At this
+ time, Amazon DynamoDB is available only in the US-EAST-1 region. The
+ ``connect_dynamodb`` method automatically connect to that region.
+
+The :py:func:`boto.connect_dynamodb` functions returns a
+:py:class:`boto.dynamodb.layer2.Layer2` instance, which is a high-level API
+for working with DynamoDB. Layer2 is a set of abstractions that sit atop
+the lower level :py:class:`boto.dynamodb.layer1.Layer1` API, which closely
+mirrors the Amazon DynamoDB API. For the purpose of this tutorial, we'll
+just be covering Layer2.
+
+Listing Tables
+--------------
+
+Now that we have a DynamoDB connection object, we can then query for a list of
+existing tables in that region::
+
+ >>> conn.list_tables()
+ ['test-table', 'another-table']
+
+Creating Tables
+---------------
+
+DynamoDB tables are created with the
+:py:meth:`Layer2.create_table <boto.dynamodb.layer2.Layer2.create_table>`
+method. While DynamoDB's items (a rough equivalent to a relational DB's row)
+don't have a fixed schema, you do need to create a schema for the table's
+hash key element, and the optional range key element. This is explained in
+greater detail in DynamoDB's `Data Model`_ documentation.
+
+We'll start by defining a schema that has a hash key and a range key that
+are both keys::
+
+ >>> message_table_schema = conn.create_schema(
+ hash_key_name='forum_name',
+ hash_key_proto_value='S',
+ range_key_name='subject',
+ range_key_proto_value='S'
+ )
+
+The next few things to determine are table name and read/write throughput. We'll
+defer explaining throughput to the DynamoDB's `Provisioned Throughput`_ docs.
+
+We're now ready to create the table::
+
+ >>> table = conn.create_table(
+ name='messages',
+ schema=message_table_schema,
+ read_units=10,
+ write_units=10
+ )
+ >>> table
+ Table(messages)
+
+This returns a :py:class:`boto.dynamodb.table.Table` instance, which provides
+simple ways to create (put), update, and delete items.
+
+.. _Data Model: http://docs.amazonwebservices.com/amazondynamodb/latest/developerguide/DataModel.html
+.. _Provisioned Throughput: http://docs.amazonwebservices.com/amazondynamodb/latest/developerguide/ProvisionedThroughputIntro.html
+
+Getting a Table
+---------------
+
+To retrieve an existing table, use
+:py:meth:`Layer2.get_table <boto.dynamodb.layer2.Layer2.get_table>`::
+
+ >>> conn.list_tables()
+ ['test-table', 'another-table', 'messages']
+ >>> table = conn.get_table('messages')
+ >>> table
+ Table(messages)
+
+:py:meth:`Layer2.get_table <boto.dynamodb.layer2.Layer2.get_table>`, like
+:py:meth:`Layer2.create_table <boto.dynamodb.layer2.Layer2.create_table>`,
+returns a :py:class:`boto.dynamodb.table.Table` instance.
+
+Describing Tables
+-----------------
+
+To get a complete description of a table, use
+:py:meth:`Layer2.describe_table <boto.dynamodb.layer2.Layer2.describe_table>`::
+
+ >>> conn.list_tables()
+ ['test-table', 'another-table', 'messages']
+ >>> conn.describe_table('messages')
+ {
+ 'Table': {
+ 'CreationDateTime': 1327117581.624,
+ 'ItemCount': 0,
+ 'KeySchema': {
+ 'HashKeyElement': {
+ 'AttributeName': 'forum_name',
+ 'AttributeType': 'S'
+ },
+ 'RangeKeyElement': {
+ 'AttributeName': 'subject',
+ 'AttributeType': 'S'
+ }
+ },
+ 'ProvisionedThroughput': {
+ 'ReadCapacityUnits': 10,
+ 'WriteCapacityUnits': 10
+ },
+ 'TableName': 'messages',
+ 'TableSizeBytes': 0,
+ 'TableStatus': 'ACTIVE'
+ }
+ }
+
+Adding Items
+------------
+
+Continuing on with our previously created ``messages`` table, adding an::
+
+ >>> table = conn.get_table('messages')
+ >>> item_data = {
+ 'Body': 'http://url_to_lolcat.gif',
+ 'SentBy': 'User A',
+ 'ReceivedTime': '12/9/2011 11:36:03 PM',
+ }
+ >>> item = table.new_item(
+ # Our hash key is 'forum'
+ hash_key='LOLCat Forum',
+ # Our range key is 'subject'
+ range_key='Check this out!',
+ # This has the
+ attrs=item_data
+ )
+
+The
+:py:meth:`Table.new_item <boto.dynamodb.table.Table.new_item>` method creates
+a new :py:class:`boto.dynamodb.item.Item` instance with your specified
+hash key, range key, and attributes already set.
+:py:class:`Item <boto.dynamodb.item.Item>` is a :py:class:`dict` sub-class,
+meaning you can edit your data as such::
+
+ item['a_new_key'] = 'testing'
+ del item['a_new_key']
+
+After you are happy with the contents of the item, use
+:py:meth:`Item.put <boto.dynamodb.item.Item.put>` to commit it to DynamoDB::
+
+ >>> item.put()
+
+Retrieving Items
+----------------
+
+Now, let's check if it got added correctly. Since DynamoDB works under an
+'eventual consistency' mode, we need to specify that we wish a consistent read,
+as follows::
+
+ >>> table = conn.get_table('messages')
+ >>> item = table.get_item(
+ # Your hash key was 'forum_name'
+ hash_key='LOLCat Forum',
+ # Your range key was 'subject'
+ range_key='Check this out!'
+ )
+ >>> item
+ {
+ # Note that this was your hash key attribute (forum_name)
+ 'forum_name': 'LOLCat Forum',
+ # This is your range key attribute (subject)
+ 'subject': 'Check this out!'
+ 'Body': 'http://url_to_lolcat.gif',
+ 'ReceivedTime': '12/9/2011 11:36:03 PM',
+ 'SentBy': 'User A',
+ }
+
+Updating Items
+--------------
+
+To update an item's attributes, simply retrieve it, modify the value, then
+:py:meth:`Item.put <boto.dynamodb.item.Item.put>` it again::
+
+ >>> table = conn.get_table('messages')
+ >>> item = table.get_item(
+ hash_key='LOLCat Forum',
+ range_key='Check this out!'
+ )
+ >>> item['SentBy'] = 'User B'
+ >>> item.put()
+
+Deleting Items
+--------------
+
+To delete items, use the
+:py:meth:`Item.delete <boto.dynamodb.item.Item.delete>` method::
+
+ >>> table = conn.get_table('messages')
+ >>> item = table.get_item(
+ hash_key='LOLCat Forum',
+ range_key='Check this out!'
+ )
+ >>> item.delete()
+
+Deleting Tables
+---------------
+
+.. WARNING::
+ Deleting a table will also **permanently** delete all of its contents without prompt. Use carefully.
+
+There are two easy ways to delete a table. Through your top-level
+:py:class:`Layer2 <boto.dynamodb.layer2.Layer2>` object::
+
+ >>> conn.delete_table(table)
+
+Or by getting the table, then using
+:py:meth:`Table.delete <boto.dynamodb.table.Table.delete>`::
+
+ >>> table = conn.get_table('messages')
+ >>> table.delete()
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