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monasca-agent
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monasca-agent/monagent/checks/libs/boto/dynamodb2/layer1.py

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# Copyright (c) 2013 Amazon.com, Inc. or its affiliates. All Rights Reserved
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish, dis-
# tribute, sublicense, and/or sell copies of the Software, and to permit
# persons to whom the Software is furnished to do so, subject to the fol-
# lowing conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABIL-
# ITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
# SHALL THE AUTHOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
# IN THE SOFTWARE.
#
from binascii import crc32
try:
import json
except ImportError:
import simplejson as json
import boto
from boto.connection import AWSQueryConnection
from boto.regioninfo import RegionInfo
from boto.exception import JSONResponseError
from boto.dynamodb2 import exceptions
class DynamoDBConnection(AWSQueryConnection):
"""
Amazon DynamoDB is a fast, highly scalable, highly available,
cost-effective non-relational database service. Amazon DynamoDB
removes traditional scalability limitations on data storage while
maintaining low latency and predictable performance.
"""
APIVersion = "2012-08-10"
DefaultRegionName = "us-east-1"
DefaultRegionEndpoint = "dynamodb.us-east-1.amazonaws.com"
ServiceName = "DynamoDB"
TargetPrefix = "DynamoDB_20120810"
ResponseError = JSONResponseError
_faults = {
"ProvisionedThroughputExceededException": exceptions.ProvisionedThroughputExceededException,
"LimitExceededException": exceptions.LimitExceededException,
"ConditionalCheckFailedException": exceptions.ConditionalCheckFailedException,
"ResourceInUseException": exceptions.ResourceInUseException,
"ResourceNotFoundException": exceptions.ResourceNotFoundException,
"InternalServerError": exceptions.InternalServerError,
"ItemCollectionSizeLimitExceededException": exceptions.ItemCollectionSizeLimitExceededException,
"ValidationException": exceptions.ValidationException,
}
NumberRetries = 10
def __init__(self, **kwargs):
region = kwargs.pop('region', None)
validate_checksums = kwargs.pop('validate_checksums', True)
if not region:
region_name = boto.config.get('DynamoDB', 'region',
self.DefaultRegionName)
for reg in boto.dynamodb2.regions():
if reg.name == region_name:
region = reg
break
# Only set host if it isn't manually overwritten
if 'host' not in kwargs:
kwargs['host'] = region.endpoint
AWSQueryConnection.__init__(self, **kwargs)
self.region = region
self._validate_checksums = boto.config.getbool(
'DynamoDB', 'validate_checksums', validate_checksums)
self.throughput_exceeded_events = 0
def _required_auth_capability(self):
return ['hmac-v4']
def batch_get_item(self, request_items, return_consumed_capacity=None):
"""
The BatchGetItem operation returns the attributes of one or
more items from one or more tables. You identify requested
items by primary key.
A single operation can retrieve up to 1 MB of data, which can
comprise as many as 100 items. BatchGetItem will return a
partial result if the response size limit is exceeded, the
table's provisioned throughput is exceeded, or an internal
processing failure occurs. If a partial result is returned,
the operation returns a value for UnprocessedKeys . You can
use this value to retry the operation starting with the next
item to get.
For example, if you ask to retrieve 100 items, but each
individual item is 50 KB in size, the system returns 20 items
(1 MB) and an appropriate UnprocessedKeys value so you can get
the next page of results. If desired, your application can
include its own logic to assemble the pages of results into
one dataset.
If no items can be processed because of insufficient
provisioned throughput on each of the tables involved in the
request, BatchGetItem throws
ProvisionedThroughputExceededException .
By default, BatchGetItem performs eventually consistent reads
on every table in the request. If you want strongly consistent
reads instead, you can set ConsistentRead to `True` for any or
all tables.
In order to minimize response latency, BatchGetItem fetches
items in parallel.
When designing your application, keep in mind that Amazon
DynamoDB does not return attributes in any particular order.
To help parse the response by item, include the primary key
values for the items in your request in the AttributesToGet
parameter.
If a requested item does not exist, it is not returned in the
result. Requests for nonexistent items consume the minimum
read capacity units according to the type of read. For more
information, see `Capacity Units Calculations`_ in the Amazon
DynamoDB Developer Guide .
:type request_items: map
:param request_items:
A map of one or more table names and, for each table, the corresponding
primary keys for the items to retrieve. Each table name can be
invoked only once.
Each element in the map consists of the following:
+ Keys - An array of primary key attribute values that define specific
items in the table.
+ AttributesToGet - One or more attributes to be retrieved from the
table or index. By default, all attributes are returned. If a
specified attribute is not found, it does not appear in the result.
+ ConsistentRead - If `True`, a strongly consistent read is used; if
`False` (the default), an eventually consistent read is used.
:type return_consumed_capacity: string
:param return_consumed_capacity:
"""
params = {'RequestItems': request_items, }
if return_consumed_capacity is not None:
params['ReturnConsumedCapacity'] = return_consumed_capacity
return self.make_request(action='BatchGetItem',
body=json.dumps(params))
def batch_write_item(self, request_items, return_consumed_capacity=None,
return_item_collection_metrics=None):
"""
The BatchWriteItem operation puts or deletes multiple items in
one or more tables. A single call to BatchWriteItem can write
up to 1 MB of data, which can comprise as many as 25 put or
delete requests. Individual items to be written can be as
large as 64 KB.
BatchWriteItem cannot update items. To update items, use the
UpdateItem API.
The individual PutItem and DeleteItem operations specified in
BatchWriteItem are atomic; however BatchWriteItem as a whole
is not. If any requested operations fail because the table's
provisioned throughput is exceeded or an internal processing
failure occurs, the failed operations are returned in the
UnprocessedItems response parameter. You can investigate and
optionally resend the requests. Typically, you would call
BatchWriteItem in a loop. Each iteration would check for
unprocessed items and submit a new BatchWriteItem request with
those unprocessed items until all items have been processed.
To write one item, you can use the PutItem operation; to
delete one item, you can use the DeleteItem operation.
With BatchWriteItem , you can efficiently write or delete
large amounts of data, such as from Amazon Elastic MapReduce
(EMR), or copy data from another database into Amazon
DynamoDB. In order to improve performance with these large-
scale operations, BatchWriteItem does not behave in the same
way as individual PutItem and DeleteItem calls would For
example, you cannot specify conditions on individual put and
delete requests, and BatchWriteItem does not return deleted
items in the response.
If you use a programming language that supports concurrency,
such as Java, you can use threads to write items in parallel.
Your application must include the necessary logic to manage
the threads.
With languages that don't support threading, such as PHP,
BatchWriteItem will write or delete the specified items one at
a time. In both situations, BatchWriteItem provides an
alternative where the API performs the specified put and
delete operations in parallel, giving you the power of the
thread pool approach without having to introduce complexity
into your application.
Parallel processing reduces latency, but each specified put
and delete request consumes the same number of write capacity
units whether it is processed in parallel or not. Delete
operations on nonexistent items consume one write capacity
unit.
If one or more of the following is true, Amazon DynamoDB
rejects the entire batch write operation:
+ One or more tables specified in the BatchWriteItem request
does not exist.
+ Primary key attributes specified on an item in the request
do not match those in the corresponding table's primary key
schema.
+ You try to perform multiple operations on the same item in
the same BatchWriteItem request. For example, you cannot put
and delete the same item in the same BatchWriteItem request.
+ The total request size exceeds 1 MB.
+ Any individual item in a batch exceeds 64 KB.
:type request_items: map
:param request_items:
A map of one or more table names and, for each table, a list of
operations to be performed ( DeleteRequest or PutRequest ). Each
element in the map consists of the following:
+ DeleteRequest - Perform a DeleteItem operation on the specified item.
The item to be deleted is identified by a Key subelement:
+ Key - A map of primary key attribute values that uniquely identify
the item. Each entry in this map consists of an attribute name and
an attribute value.
+ PutRequest - Perform a PutItem operation on the specified item. The
item to be put is identified by an Item subelement:
+ Item - A map of attributes and their values. Each entry in this map
consists of an attribute name and an attribute value. Attribute
values must not be null; string and binary type attributes must
have lengths greater than zero; and set type attributes must not be
empty. Requests that contain empty values will be rejected with a
ValidationException . If you specify any attributes that are part
of an index key, then the data types for those attributes must
match those of the schema in the table's attribute definition.
:type return_consumed_capacity: string
:param return_consumed_capacity:
:type return_item_collection_metrics: string
:param return_item_collection_metrics: If set to `SIZE`, statistics
about item collections, if any, that were modified during the
operation are returned in the response. If set to `NONE` (the
default), no statistics are returned..
"""
params = {'RequestItems': request_items, }
if return_consumed_capacity is not None:
params['ReturnConsumedCapacity'] = return_consumed_capacity
if return_item_collection_metrics is not None:
params['ReturnItemCollectionMetrics'] = return_item_collection_metrics
return self.make_request(action='BatchWriteItem',
body=json.dumps(params))
def create_table(self, attribute_definitions, table_name, key_schema,
provisioned_throughput, local_secondary_indexes=None):
"""
The CreateTable operation adds a new table to your account. In
an AWS account, table names must be unique within each region.
That is, you can have two tables with same name if you create
the tables in different regions.
CreateTable is an asynchronous operation. Upon receiving a
CreateTable request, Amazon DynamoDB immediately returns a
response with a TableStatus of `CREATING`. After the table is
created, Amazon DynamoDB sets the TableStatus to `ACTIVE`. You
can perform read and write operations only on an `ACTIVE`
table.
If you want to create multiple tables with local secondary
indexes on them, you must create them sequentially. Only one
table with local secondary indexes can be in the `CREATING`
state at any given time.
You can use the DescribeTable API to check the table status.
:type attribute_definitions: list
:param attribute_definitions: An array of attributes that describe the
key schema for the table and indexes.
:type table_name: string
:param table_name: The name of the table to create.
:type key_schema: list
:param key_schema: Specifies the attributes that make up the primary
key for the table. The attributes in KeySchema must also be defined
in the AttributeDefinitions array. For more information, see `Data
Model`_ in the Amazon DynamoDB Developer Guide .
Each KeySchemaElement in the array is composed of:
+ AttributeName - The name of this key attribute.
+ KeyType - Determines whether the key attribute is `HASH` or `RANGE`.
For a primary key that consists of a hash attribute, you must specify
exactly one element with a KeyType of `HASH`.
For a primary key that consists of hash and range attributes, you must
specify exactly two elements, in this order: The first element must
have a KeyType of `HASH`, and the second element must have a
KeyType of `RANGE`.
For more information, see `Specifying the Primary Key`_ in the Amazon
DynamoDB Developer Guide .
:type local_secondary_indexes: list
:param local_secondary_indexes:
One or more secondary indexes (the maximum is five) to be created on
the table. Each index is scoped to a given hash key value. There is
a 10 gigabyte size limit per hash key; otherwise, the size of a
local secondary index is unconstrained.
Each secondary index in the array includes the following:
+ IndexName - The name of the secondary index. Must be unique only for
this table.
+ KeySchema - Specifies the key schema for the index. The key schema
must begin with the same hash key attribute as the table.
+ Projection - Specifies attributes that are copied (projected) from
the table into the index. These are in addition to the primary key
attributes and index key attributes, which are automatically
projected. Each attribute specification is composed of:
+ ProjectionType - One of the following:
+ `KEYS_ONLY` - Only the index and primary keys are projected into the
index.
+ `INCLUDE` - Only the specified table attributes are projected into
the index. The list of projected attributes are in NonKeyAttributes
.
+ `ALL` - All of the table attributes are projected into the index.
+ NonKeyAttributes - A list of one or more non-key attribute names that
are projected into the index. The total count of attributes
specified in NonKeyAttributes , summed across all of the local
secondary indexes, must not exceed 20. If you project the same
attribute into two different indexes, this counts as two distinct
attributes when determining the total.
:type provisioned_throughput: dict
:param provisioned_throughput:
"""
params = {
'AttributeDefinitions': attribute_definitions,
'TableName': table_name,
'KeySchema': key_schema,
'ProvisionedThroughput': provisioned_throughput,
}
if local_secondary_indexes is not None:
params['LocalSecondaryIndexes'] = local_secondary_indexes
return self.make_request(action='CreateTable',
body=json.dumps(params))
def delete_item(self, table_name, key, expected=None, return_values=None,
return_consumed_capacity=None,
return_item_collection_metrics=None):
"""
Deletes a single item in a table by primary key. You can
perform a conditional delete operation that deletes the item
if it exists, or if it has an expected attribute value.
In addition to deleting an item, you can also return the
item's attribute values in the same operation, using the
ReturnValues parameter.
Unless you specify conditions, the DeleteItem is an idempotent
operation; running it multiple times on the same item or
attribute does not result in an error response.
Conditional deletes are useful for only deleting items if
specific conditions are met. If those conditions are met,
Amazon DynamoDB performs the delete. Otherwise, the item is
not deleted.
:type table_name: string
:param table_name: The name of the table from which to delete the item.
:type key: map
:param key: A map of attribute names to AttributeValue objects,
representing the primary key of the item to delete.
:type expected: map
:param expected: A map of attribute/condition pairs. This is the
conditional block for the DeleteItem operation. All the conditions
must be met for the operation to succeed.
Expected allows you to provide an attribute name, and whether or not
Amazon DynamoDB should check to see if the attribute value already
exists; or if the attribute value exists and has a particular value
before changing it.
Each item in Expected represents an attribute name for Amazon DynamoDB
to check, along with the following:
+ Value - The attribute value for Amazon DynamoDB to check.
+ Exists - Causes Amazon DynamoDB to evaluate the value before
attempting a conditional operation:
+ If Exists is `True`, Amazon DynamoDB will check to see if that
attribute value already exists in the table. If it is found, then
the operation succeeds. If it is not found, the operation fails
with a ConditionalCheckFailedException .
+ If Exists is `False`, Amazon DynamoDB assumes that the attribute
value does not exist in the table. If in fact the value does not
exist, then the assumption is valid and the operation succeeds. If
the value is found, despite the assumption that it does not exist,
the operation fails with a ConditionalCheckFailedException .
The default setting for Exists is `True`. If you supply a Value all by
itself, Amazon DynamoDB assumes the attribute exists: You don't
have to set Exists to `True`, because it is implied. Amazon
DynamoDB returns a ValidationException if:
+ Exists is `True` but there is no Value to check. (You expect a value
to exist, but don't specify what that value is.)
+ Exists is `False` but you also specify a Value . (You cannot expect
an attribute to have a value, while also expecting it not to
exist.)
If you specify more than one condition for Exists , then all of the
conditions must evaluate to true. (In other words, the conditions
are ANDed together.) Otherwise, the conditional operation will
fail.
:type return_values: string
:param return_values:
Use ReturnValues if you want to get the item attributes as they
appeared before they were deleted. For DeleteItem , the valid
values are:
+ `NONE` - If ReturnValues is not specified, or if its value is `NONE`,
then nothing is returned. (This is the default for ReturnValues .)
+ `ALL_OLD` - The content of the old item is returned.
:type return_consumed_capacity: string
:param return_consumed_capacity:
:type return_item_collection_metrics: string
:param return_item_collection_metrics: If set to `SIZE`, statistics
about item collections, if any, that were modified during the
operation are returned in the response. If set to `NONE` (the
default), no statistics are returned..
"""
params = {'TableName': table_name, 'Key': key, }
if expected is not None:
params['Expected'] = expected
if return_values is not None:
params['ReturnValues'] = return_values
if return_consumed_capacity is not None:
params['ReturnConsumedCapacity'] = return_consumed_capacity
if return_item_collection_metrics is not None:
params['ReturnItemCollectionMetrics'] = return_item_collection_metrics
return self.make_request(action='DeleteItem',
body=json.dumps(params))
def delete_table(self, table_name):
"""
The DeleteTable operation deletes a table and all of its
items. After a DeleteTable request, the specified table is in
the `DELETING` state until Amazon DynamoDB completes the
deletion. If the table is in the `ACTIVE` state, you can
delete it. If a table is in `CREATING` or `UPDATING` states,
then Amazon DynamoDB returns a ResourceInUseException . If the
specified table does not exist, Amazon DynamoDB returns a
ResourceNotFoundException . If table is already in the
`DELETING` state, no error is returned.
Amazon DynamoDB might continue to accept data read and write
operations, such as GetItem and PutItem , on a table in the
`DELETING` state until the table deletion is complete.
Tables are unique among those associated with the AWS Account
issuing the request, and the AWS region that receives the
request (such as dynamodb.us-east-1.amazonaws.com). Each
Amazon DynamoDB endpoint is entirely independent. For example,
if you have two tables called "MyTable," one in dynamodb.us-
east-1.amazonaws.com and one in dynamodb.us-
west-1.amazonaws.com, they are completely independent and do
not share any data; deleting one does not delete the other.
When you delete a table, any local secondary indexes on that
table are also deleted.
Use the DescribeTable API to check the status of the table.
:type table_name: string
:param table_name: The name of the table to delete.
"""
params = {'TableName': table_name, }
return self.make_request(action='DeleteTable',
body=json.dumps(params))
def describe_table(self, table_name):
"""
Returns information about the table, including the current
status of the table, when it was created, the primary key
schema, and any indexes on the table.
:type table_name: string
:param table_name: The name of the table to describe.
"""
params = {'TableName': table_name, }
return self.make_request(action='DescribeTable',
body=json.dumps(params))
def get_item(self, table_name, key, attributes_to_get=None,
consistent_read=None, return_consumed_capacity=None):
"""
The GetItem operation returns a set of attributes for the item
with the given primary key. If there is no matching item,
GetItem does not return any data.
GetItem provides an eventually consistent read by default. If
your application requires a strongly consistent read, set
ConsistentRead to `True`. Although a strongly consistent read
might take more time than an eventually consistent read, it
always returns the last updated value.
:type table_name: string
:param table_name: The name of the table containing the requested item.
:type key: map
:param key: A map of attribute names to AttributeValue objects,
representing the primary key of the item to retrieve.
:type attributes_to_get: list
:param attributes_to_get: The names of one or more attributes to
retrieve. If no attribute names are specified, then all attributes
will be returned. If any of the requested attributes are not found,
they will not appear in the result.
:type consistent_read: boolean
:param consistent_read: If set to `True`, then the operation uses
strongly consistent reads; otherwise, eventually consistent reads
are used.
:type return_consumed_capacity: string
:param return_consumed_capacity:
"""
params = {'TableName': table_name, 'Key': key, }
if attributes_to_get is not None:
params['AttributesToGet'] = attributes_to_get
if consistent_read is not None:
params['ConsistentRead'] = consistent_read
if return_consumed_capacity is not None:
params['ReturnConsumedCapacity'] = return_consumed_capacity
return self.make_request(action='GetItem',
body=json.dumps(params))
def list_tables(self, exclusive_start_table_name=None, limit=None):
"""
Returns an array of all the tables associated with the current
account and endpoint.
Each Amazon DynamoDB endpoint is entirely independent. For
example, if you have two tables called "MyTable," one in
dynamodb.us-east-1.amazonaws.com and one in dynamodb.us-
west-1.amazonaws.com , they are completely independent and do
not share any data. The ListTables operation returns all of
the table names associated with the account making the
request, for the endpoint that receives the request.
:type exclusive_start_table_name: string
:param exclusive_start_table_name: The name of the table that starts
the list. If you already ran a ListTables operation and received a
LastEvaluatedTableName value in the response, use that value here
to continue the list.
:type limit: integer
:param limit: A maximum number of table names to return.
"""
params = {}
if exclusive_start_table_name is not None:
params['ExclusiveStartTableName'] = exclusive_start_table_name
if limit is not None:
params['Limit'] = limit
return self.make_request(action='ListTables',
body=json.dumps(params))
def put_item(self, table_name, item, expected=None, return_values=None,
return_consumed_capacity=None,
return_item_collection_metrics=None):
"""
Creates a new item, or replaces an old item with a new item.
If an item already exists in the specified table with the same
primary key, the new item completely replaces the existing
item. You can perform a conditional put (insert a new item if
one with the specified primary key doesn't exist), or replace
an existing item if it has certain attribute values.
In addition to putting an item, you can also return the item's
attribute values in the same operation, using the ReturnValues
parameter.
When you add an item, the primary key attribute(s) are the
only required attributes. Attribute values cannot be null.
String and binary type attributes must have lengths greater
than zero. Set type attributes cannot be empty. Requests with
empty values will be rejected with a ValidationException .
You can request that PutItem return either a copy of the old
item (before the update) or a copy of the new item (after the
update). For more information, see the ReturnValues
description.
To prevent a new item from replacing an existing item, use a
conditional put operation with Exists set to `False` for the
primary key attribute, or attributes.
For more information about using this API, see `Working with
Items`_ in the Amazon DynamoDB Developer Guide .
:type table_name: string
:param table_name: The name of the table to contain the item.
:type item: map
:param item: A map of attribute name/value pairs, one for each
attribute. Only the primary key attributes are required; you can
optionally provide other attribute name-value pairs for the item.
If you specify any attributes that are part of an index key, then the
data types for those attributes must match those of the schema in
the table's attribute definition.
For more information about primary keys, see `Primary Key`_ in the
Amazon DynamoDB Developer Guide .
Each element in the Item map is an AttributeValue object.
:type expected: map
:param expected: A map of attribute/condition pairs. This is the
conditional block for the PutItem operation. All the conditions
must be met for the operation to succeed.
Expected allows you to provide an attribute name, and whether or not
Amazon DynamoDB should check to see if the attribute value already
exists; or if the attribute value exists and has a particular value
before changing it.
Each item in Expected represents an attribute name for Amazon DynamoDB
to check, along with the following:
+ Value - The attribute value for Amazon DynamoDB to check.
+ Exists - Causes Amazon DynamoDB to evaluate the value before
attempting a conditional operation:
+ If Exists is `True`, Amazon DynamoDB will check to see if that
attribute value already exists in the table. If it is found, then
the operation succeeds. If it is not found, the operation fails
with a ConditionalCheckFailedException .
+ If Exists is `False`, Amazon DynamoDB assumes that the attribute
value does not exist in the table. If in fact the value does not
exist, then the assumption is valid and the operation succeeds. If
the value is found, despite the assumption that it does not exist,
the operation fails with a ConditionalCheckFailedException .
The default setting for Exists is `True`. If you supply a Value all by
itself, Amazon DynamoDB assumes the attribute exists: You don't
have to set Exists to `True`, because it is implied. Amazon
DynamoDB returns a ValidationException if:
+ Exists is `True` but there is no Value to check. (You expect a value
to exist, but don't specify what that value is.)
+ Exists is `False` but you also specify a Value . (You cannot expect
an attribute to have a value, while also expecting it not to
exist.)
If you specify more than one condition for Exists , then all of the
conditions must evaluate to true. (In other words, the conditions
are ANDed together.) Otherwise, the conditional operation will
fail.
:type return_values: string
:param return_values:
Use ReturnValues if you want to get the item attributes as they
appeared before they were updated with the PutItem request. For
PutItem , the valid values are:
+ `NONE` - If ReturnValues is not specified, or if its value is `NONE`,
then nothing is returned. (This is the default for ReturnValues .)
+ `ALL_OLD` - If PutItem overwrote an attribute name-value pair, then
the content of the old item is returned.
:type return_consumed_capacity: string
:param return_consumed_capacity:
:type return_item_collection_metrics: string
:param return_item_collection_metrics: If set to `SIZE`, statistics
about item collections, if any, that were modified during the
operation are returned in the response. If set to `NONE` (the
default), no statistics are returned..
"""
params = {'TableName': table_name, 'Item': item, }
if expected is not None:
params['Expected'] = expected
if return_values is not None:
params['ReturnValues'] = return_values
if return_consumed_capacity is not None:
params['ReturnConsumedCapacity'] = return_consumed_capacity
if return_item_collection_metrics is not None:
params['ReturnItemCollectionMetrics'] = return_item_collection_metrics
return self.make_request(action='PutItem',
body=json.dumps(params))
def query(self, table_name, index_name=None, select=None,
attributes_to_get=None, limit=None, consistent_read=None,
key_conditions=None, scan_index_forward=None,
exclusive_start_key=None, return_consumed_capacity=None):
"""
A Query operation directly accesses items from a table using
the table primary key, or from an index using the index key.
You must provide a specific hash key value. You can narrow the
scope of the query by using comparison operators on the range
key value, or on the index key. You can use the
ScanIndexForward parameter to get results in forward or
reverse order, by range key or by index key.
Queries that do not return results consume the minimum read
capacity units according to the type of read.
If the total number of items meeting the query criteria
exceeds the result set size limit of 1 MB, the query stops and
results are returned to the user with a LastEvaluatedKey to
continue the query in a subsequent operation. Unlike a Scan
operation, a Query operation never returns an empty result set
and a LastEvaluatedKey . The LastEvaluatedKey is only provided
if the results exceed 1 MB, or if you have used Limit .
To request a strongly consistent result, set ConsistentRead to
true.
:type table_name: string
:param table_name: The name of the table containing the requested
items.
:type index_name: string
:param index_name: The name of an index on the table to query.
:type select: string
:param select: The attributes to be returned in the result. You can
retrieve all item attributes, specific item attributes, the count
of matching items, or in the case of an index, some or all of the
attributes projected into the index.
+ `ALL_ATTRIBUTES`: Returns all of the item attributes. For a table,
this is the default. For an index, this mode causes Amazon DynamoDB
to fetch the full item from the table for each matching item in the
index. If the index is configured to project all item attributes,
the matching items will not be fetched from the table. Fetching
items from the table incurs additional throughput cost and latency.
+ `ALL_PROJECTED_ATTRIBUTES`: Allowed only when querying an index.
Retrieves all attributes which have been projected into the index.
If the index is configured to project all attributes, this is
equivalent to specifying ALL_ATTRIBUTES .
+ `COUNT`: Returns the number of matching items, rather than the
matching items themselves.
+ `SPECIFIC_ATTRIBUTES` : Returns only the attributes listed in
AttributesToGet . This is equivalent to specifying AttributesToGet
without specifying any value for Select . If you are querying an
index and request only attributes that are projected into that
index, the operation will read only the index and not the table. If
any of the requested attributes are not projected into the index,
Amazon DynamoDB will need to fetch each matching item from the
table. This extra fetching incurs additional throughput cost and
latency.
When neither Select nor AttributesToGet are specified, Amazon DynamoDB
defaults to `ALL_ATTRIBUTES` when accessing a table, and
`ALL_PROJECTED_ATTRIBUTES` when accessing an index. You cannot use
both Select and AttributesToGet together in a single request,
unless the value for Select is `SPECIFIC_ATTRIBUTES`. (This usage
is equivalent to specifying AttributesToGet without any value for
Select .)
:type attributes_to_get: list
:param attributes_to_get: The names of one or more attributes to
retrieve. If no attribute names are specified, then all attributes
will be returned. If any of the requested attributes are not found,
they will not appear in the result.
If you are querying an index and request only attributes that are
projected into that index, the operation will read only the index
and not the table. If any of the requested attributes are not
projected into the index, Amazon DynamoDB will need to fetch each
matching item from the table. This extra fetching incurs additional
throughput cost and latency.
You cannot use both AttributesToGet and Select together in a Query
request, unless the value for Select is `SPECIFIC_ATTRIBUTES`.
(This usage is equivalent to specifying AttributesToGet without any
value for Select .)
:type limit: integer
:param limit: The maximum number of items to evaluate (not necessarily
the number of matching items). If Amazon DynamoDB processes the
number of items up to the limit while processing the results, it
stops the operation and returns the matching values up to that
point, and a LastEvaluatedKey to apply in a subsequent operation,
so that you can pick up where you left off. Also, if the processed
data set size exceeds 1 MB before Amazon DynamoDB reaches this
limit, it stops the operation and returns the matching values up to
the limit, and a LastEvaluatedKey to apply in a subsequent
operation to continue the operation. For more information see
`Query and Scan`_ in the Amazon DynamoDB Developer Guide .
:type consistent_read: boolean
:param consistent_read: If set to `True`, then the operation uses
strongly consistent reads; otherwise, eventually consistent reads
are used.
:type key_conditions: map
:param key_conditions:
The selection criteria for the query.
For a query on a table, you can only have conditions on the table
primary key attributes. you must specify the hash key attribute
name and value as an `EQ` condition. You can optionally specify a
second condition, referring to the range key attribute.
For a query on a secondary index, you can only have conditions on the
index key attributes. You must specify the index hash attribute
name and value as an EQ condition. You can optionally specify a
second condition, referring to the index key range attribute.
Multiple conditions are evaluated using "AND"; in other words, all of
the conditions must be met in order for an item to appear in the
results results.
Each KeyConditions element consists of an attribute name to compare,
along with the following:
+ AttributeValueList - One or more values to evaluate against the
supplied attribute. This list contains exactly one value, except
for a `BETWEEN` or `IN` comparison, in which case the list contains
two values. For type Number, value comparisons are numeric. String
value comparisons for greater than, equals, or less than are based
on ASCII character code values. For example, `a` is greater than
`A`, and `aa` is greater than `B`. For a list of code values, see
`http://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters`_.
For Binary, Amazon DynamoDB treats each byte of the binary data as
unsigned when it compares binary values, for example when
evaluating query expressions.
+ ComparisonOperator - A comparator for evaluating attributes. For
example, equals, greater than, less than, etc. Valid comparison
operators for Query: `EQ | LE | LT | GE | GT | BEGINS_WITH |
BETWEEN` For information on specifying data types in JSON, see
`JSON Data Format`_ in the Amazon DynamoDB Developer Guide . The
following are descriptions of each comparison operator.
+ `EQ` : Equal. AttributeValueList can contain only one AttributeValue
of type String, Number, or Binary (not a set). If an item contains
an AttributeValue of a different type than the one specified in the
request, the value does not match. For example, `{"S":"6"}` does
not equal `{"N":"6"}`. Also, `{"N":"6"}` does not equal
`{"NS":["6", "2", "1"]}`.
+ `LE` : Less than or equal. AttributeValueList can contain only one
AttributeValue of type String, Number, or Binary (not a set). If an
item contains an AttributeValue of a different type than the one
specified in the request, the value does not match. For example,
`{"S":"6"}` does not equal `{"N":"6"}`. Also, `{"N":"6"}` does not
compare to `{"NS":["6", "2", "1"]}`.
+ `LT` : Less than. AttributeValueList can contain only one
AttributeValue of type String, Number, or Binary (not a set). If an
item contains an AttributeValue of a different type than the one
specified in the request, the value does not match. For example,
`{"S":"6"}` does not equal `{"N":"6"}`. Also, `{"N":"6"}` does not
compare to `{"NS":["6", "2", "1"]}`.
+ `GE` : Greater than or equal. AttributeValueList can contain only one
AttributeValue of type String, Number, or Binary (not a set). If an
item contains an AttributeValue of a different type than the one
specified in the request, the value does not match. For example,
`{"S":"6"}` does not equal `{"N":"6"}`. Also, `{"N":"6"}` does not
compare to `{"NS":["6", "2", "1"]}`.
+ `GT` : Greater than. AttributeValueList can contain only one
AttributeValue of type String, Number, or Binary (not a set). If an
item contains an AttributeValue of a different type than the one
specified in the request, the value does not match. For example,
`{"S":"6"}` does not equal `{"N":"6"}`. Also, `{"N":"6"}` does not
compare to `{"NS":["6", "2", "1"]}`.
+ `BEGINS_WITH` : checks for a prefix. AttributeValueList can contain
only one AttributeValue of type String or Binary (not a Number or a
set). The target attribute of the comparison must be a String or
Binary (not a Number or a set).
+ `BETWEEN` : Greater than or equal to the first value, and less than
or equal to the second value. AttributeValueList must contain two
AttributeValue elements of the same type, either String, Number, or
Binary (not a set). A target attribute matches if the target value
is greater than, or equal to, the first element and less than, or
equal to, the second element. If an item contains an AttributeValue
of a different type than the one specified in the request, the
value does not match. For example, `{"S":"6"}` does not compare to
`{"N":"6"}`. Also, `{"N":"6"}` does not compare to `{"NS":["6",
"2", "1"]}`
:type scan_index_forward: boolean
:param scan_index_forward: Specifies ascending (true) or descending
(false) traversal of the index. Amazon DynamoDB returns results
reflecting the requested order determined by the range key. If the
data type is Number, the results are returned in numeric order. For
String, the results are returned in order of ASCII character code
values. For Binary, Amazon DynamoDB treats each byte of the binary
data as unsigned when it compares binary values.
If ScanIndexForward is not specified, the results are returned in
ascending order.
:type exclusive_start_key: map
:param exclusive_start_key: The primary key of the item from which to
continue an earlier operation. An earlier operation might provide
this value as the LastEvaluatedKey if that operation was
interrupted before completion; either because of the result set
size or because of the setting for Limit . The LastEvaluatedKey can
be passed back in a new request to continue the operation from that
point.
The data type for ExclusiveStartKey must be String, Number or Binary.
No set data types are allowed.
:type return_consumed_capacity: string
:param return_consumed_capacity:
"""
params = {'TableName': table_name, }
if index_name is not None:
params['IndexName'] = index_name
if select is not None:
params['Select'] = select
if attributes_to_get is not None:
params['AttributesToGet'] = attributes_to_get
if limit is not None:
params['Limit'] = limit
if consistent_read is not None:
params['ConsistentRead'] = consistent_read
if key_conditions is not None:
params['KeyConditions'] = key_conditions
if scan_index_forward is not None:
params['ScanIndexForward'] = scan_index_forward
if exclusive_start_key is not None:
params['ExclusiveStartKey'] = exclusive_start_key
if return_consumed_capacity is not None:
params['ReturnConsumedCapacity'] = return_consumed_capacity
return self.make_request(action='Query',
body=json.dumps(params))
def scan(self, table_name, attributes_to_get=None, limit=None,
select=None, scan_filter=None, exclusive_start_key=None,
return_consumed_capacity=None, total_segments=None,
segment=None):
"""
The Scan operation returns one or more items and item
attributes by accessing every item in the table. To have
Amazon DynamoDB return fewer items, you can provide a
ScanFilter .
If the total number of scanned items exceeds the maximum data
set size limit of 1 MB, the scan stops and results are
returned to the user with a LastEvaluatedKey to continue the
scan in a subsequent operation. The results also include the
number of items exceeding the limit. A scan can result in no
table data meeting the filter criteria.
The result set is eventually consistent.
By default, Scan operations proceed sequentially; however, for
faster performance on large tables, applications can perform a
parallel Scan by specifying the Segment and TotalSegments
parameters. For more information, see `Parallel Scan`_ in the
Amazon DynamoDB Developer Guide .
:type table_name: string
:param table_name: The name of the table containing the requested
items.
:type attributes_to_get: list
:param attributes_to_get: The names of one or more attributes to
retrieve. If no attribute names are specified, then all attributes
will be returned. If any of the requested attributes are not found,
they will not appear in the result.
:type limit: integer
:param limit: The maximum number of items to evaluate (not necessarily
the number of matching items). If Amazon DynamoDB processes the
number of items up to the limit while processing the results, it
stops the operation and returns the matching values up to that
point, and a LastEvaluatedKey to apply in a subsequent operation,
so that you can pick up where you left off. Also, if the processed
data set size exceeds 1 MB before Amazon DynamoDB reaches this
limit, it stops the operation and returns the matching values up to
the limit, and a LastEvaluatedKey to apply in a subsequent
operation to continue the operation. For more information see
`Query and Scan`_ in the Amazon DynamoDB Developer Guide .
:type select: string
:param select: The attributes to be returned in the result. You can
retrieve all item attributes, specific item attributes, the count
of matching items, or in the case of an index, some or all of the
attributes projected into the index.
+ `ALL_ATTRIBUTES`: Returns all of the item attributes. For a table,
this is the default. For an index, this mode causes Amazon DynamoDB
to fetch the full item from the table for each matching item in the
index. If the index is configured to project all item attributes,
the matching items will not be fetched from the table. Fetching
items from the table incurs additional throughput cost and latency.
+ `ALL_PROJECTED_ATTRIBUTES`: Retrieves all attributes which have been
projected into the index. If the index is configured to project all
attributes, this is equivalent to specifying ALL_ATTRIBUTES .
+ `COUNT`: Returns the number of matching items, rather than the
matching items themselves.
+ `SPECIFIC_ATTRIBUTES` : Returns only the attributes listed in
AttributesToGet . This is equivalent to specifying AttributesToGet
without specifying any value for Select . If you are querying an
index and request only attributes that are projected into that
index, the operation will read only the index and not the table. If
any of the requested attributes are not projected into the index,
Amazon DynamoDB will need to fetch each matching item from the
table. This extra fetching incurs additional throughput cost and
latency.
When neither Select nor AttributesToGet are specified, Amazon DynamoDB
defaults to `ALL_ATTRIBUTES` when accessing a table, and
`ALL_PROJECTED_ATTRIBUTES` when accessing an index. You cannot use
both Select and AttributesToGet together in a single request,
unless the value for Select is `SPECIFIC_ATTRIBUTES`. (This usage
is equivalent to specifying AttributesToGet without any value for
Select .)
:type scan_filter: map
:param scan_filter:
Evaluates the scan results and returns only the desired values.
Multiple conditions are treated as "AND" operations: all conditions
must be met to be included in the results.
Each ScanConditions element consists of an attribute name to compare,
along with the following:
+ AttributeValueList - One or more values to evaluate against the
supplied attribute. This list contains exactly one value, except
for a `BETWEEN` or `IN` comparison, in which case the list contains
two values. For type Number, value comparisons are numeric. String
value comparisons for greater than, equals, or less than are based
on ASCII character code values. For example, `a` is greater than
`A`, and `aa` is greater than `B`. For a list of code values, see
`http://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters`_.
For Binary, Amazon DynamoDB treats each byte of the binary data as
unsigned when it compares binary values, for example when
evaluating query expressions.
+ ComparisonOperator - A comparator for evaluating attributes. For
example, equals, greater than, less than, etc. Valid comparison
operators for Scan: `EQ | NE | LE | LT | GE | GT | NOT_NULL | NULL
| CONTAINS | NOT_CONTAINS | BEGINS_WITH | IN | BETWEEN` For
information on specifying data types in JSON, see `JSON Data
Format`_ in the Amazon DynamoDB Developer Guide . The following are
descriptions of each comparison operator.
+ `EQ` : Equal. AttributeValueList can contain only one AttributeValue
of type String, Number, or Binary (not a set). If an item contains
an AttributeValue of a different type than the one specified in the
request, the value does not match. For example, `{"S":"6"}` does
not equal `{"N":"6"}`. Also, `{"N":"6"}` does not equal
`{"NS":["6", "2", "1"]}`.
+ `NE` : Not equal. AttributeValueList can contain only one
AttributeValue of type String, Number, or Binary (not a set). If an
item contains an AttributeValue of a different type than the one
specified in the request, the value does not match. For example,
`{"S":"6"}` does not equal `{"N":"6"}`. Also, `{"N":"6"}` does not
equal `{"NS":["6", "2", "1"]}`.
+ `LE` : Less than or equal. AttributeValueList can contain only one
AttributeValue of type String, Number, or Binary (not a set). If an
item contains an AttributeValue of a different type than the one
specified in the request, the value does not match. For example,
`{"S":"6"}` does not equal `{"N":"6"}`. Also, `{"N":"6"}` does not
compare to `{"NS":["6", "2", "1"]}`.
+ `LT` : Less than. AttributeValueList can contain only one
AttributeValue of type String, Number, or Binary (not a set). If an
item contains an AttributeValue of a different type than the one
specified in the request, the value does not match. For example,
`{"S":"6"}` does not equal `{"N":"6"}`. Also, `{"N":"6"}` does not
compare to `{"NS":["6", "2", "1"]}`.
+ `GE` : Greater than or equal. AttributeValueList can contain only one
AttributeValue of type String, Number, or Binary (not a set). If an
item contains an AttributeValue of a different type than the one
specified in the request, the value does not match. For example,
`{"S":"6"}` does not equal `{"N":"6"}`. Also, `{"N":"6"}` does not
compare to `{"NS":["6", "2", "1"]}`.
+ `GT` : Greater than. AttributeValueList can contain only one
AttributeValue of type String, Number, or Binary (not a set). If an
item contains an AttributeValue of a different type than the one
specified in the request, the value does not match. For example,
`{"S":"6"}` does not equal `{"N":"6"}`. Also, `{"N":"6"}` does not
compare to `{"NS":["6", "2", "1"]}`.
+ `NOT_NULL` : The attribute exists.
+ `NULL` : The attribute does not exist.
+ `CONTAINS` : checks for a subsequence, or value in a set.
AttributeValueList can contain only one AttributeValue of type
String, Number, or Binary (not a set). If the target attribute of
the comparison is a String, then the operation checks for a
substring match. If the target attribute of the comparison is
Binary, then the operation looks for a subsequence of the target
that matches the input. If the target attribute of the comparison
is a set ("SS", "NS", or "BS"), then the operation checks for a
member of the set (not as a substring).
+ `NOT_CONTAINS` : checks for absence of a subsequence, or absence of a
value in a set. AttributeValueList can contain only one
AttributeValue of type String, Number, or Binary (not a set). If
the target attribute of the comparison is a String, then the
operation checks for the absence of a substring match. If the
target attribute of the comparison is Binary, then the operation
checks for the absence of a subsequence of the target that matches
the input. If the target attribute of the comparison is a set
("SS", "NS", or "BS"), then the operation checks for the absence of
a member of the set (not as a substring).
+ `BEGINS_WITH` : checks for a prefix. AttributeValueList can contain
only one AttributeValue of type String or Binary (not a Number or a
set). The target attribute of the comparison must be a String or
Binary (not a Number or a set).
+ `IN` : checks for exact matches. AttributeValueList can contain more
than one AttributeValue of type String, Number, or Binary (not a
set). The target attribute of the comparison must be of the same
type and exact value to match. A String never matches a String set.
+ `BETWEEN` : Greater than or equal to the first value, and less than
or equal to the second value. AttributeValueList must contain two
AttributeValue elements of the same type, either String, Number, or
Binary (not a set). A target attribute matches if the target value
is greater than, or equal to, the first element and less than, or
equal to, the second element. If an item contains an AttributeValue
of a different type than the one specified in the request, the
value does not match. For example, `{"S":"6"}` does not compare to
`{"N":"6"}`. Also, `{"N":"6"}` does not compare to `{"NS":["6",
"2", "1"]}`
:type exclusive_start_key: map
:param exclusive_start_key: The primary key of the item from which to
continue an earlier operation. An earlier operation might provide
this value as the LastEvaluatedKey if that operation was
interrupted before completion; either because of the result set
size or because of the setting for Limit . The LastEvaluatedKey can
be passed back in a new request to continue the operation from that
point.
The data type for ExclusiveStartKey must be String, Number or Binary.
No set data types are allowed.
If you are performing a parallel scan, the value of ExclusiveStartKey
must fall into the key space of the Segment being scanned. For
example, suppose that there are two application threads scanning a
table using the following Scan parameters
+ Thread 0: Segment =0; TotalSegments =2
+ Thread 1: Segment =1; TotalSegments =2
Now suppose that the Scan request for Thread 0 completed and returned a
LastEvaluatedKey of "X". Because "X" is part of Segment 0's key
space, it cannot be used anywhere else in the table. If Thread 1
were to issue another Scan request with an ExclusiveStartKey of
"X", Amazon DynamoDB would throw an InputValidationError because
hash key "X" cannot be in Segment 1.
:type return_consumed_capacity: string
:param return_consumed_capacity:
:type total_segments: integer
:param total_segments: For parallel Scan requests, TotalSegments
represents the total number of segments for a table that is being
scanned. Segments are a way to logically divide a table into
equally sized portions, for the duration of the Scan request. The
value of TotalSegments corresponds to the number of application
"workers" (such as threads or processes) that will perform the
parallel Scan . For example, if you want to scan a table using four
application threads, you would specify a TotalSegments value of 4.
The value for TotalSegments must be greater than or equal to 1, and
less than or equal to 4096. If you specify a TotalSegments value of
1, the Scan will be sequential rather than parallel.
If you specify TotalSegments , you must also specify Segment .
:type segment: integer
:param segment: For parallel Scan requests, Segment identifies an
individual segment to be scanned by an application "worker" (such
as a thread or a process). Each worker issues a Scan request with a
distinct value for the segment it will scan.
Segment IDs are zero-based, so the first segment is always 0. For
example, if you want to scan a table using four application
threads, the first thread would specify a Segment value of 0, the
second thread would specify 1, and so on.
The value for Segment must be greater than or equal to 0, and less than
the value provided for TotalSegments .
If you specify Segment , you must also specify TotalSegments .
"""
params = {'TableName': table_name, }
if attributes_to_get is not None:
params['AttributesToGet'] = attributes_to_get
if limit is not None:
params['Limit'] = limit
if select is not None:
params['Select'] = select
if scan_filter is not None:
params['ScanFilter'] = scan_filter
if exclusive_start_key is not None:
params['ExclusiveStartKey'] = exclusive_start_key
if return_consumed_capacity is not None:
params['ReturnConsumedCapacity'] = return_consumed_capacity
if total_segments is not None:
params['TotalSegments'] = total_segments
if segment is not None:
params['Segment'] = segment
return self.make_request(action='Scan',
body=json.dumps(params))
def update_item(self, table_name, key, attribute_updates=None,
expected=None, return_values=None,
return_consumed_capacity=None,
return_item_collection_metrics=None):
"""
Edits an existing item's attributes, or inserts a new item if
it does not already exist. You can put, delete, or add
attribute values. You can also perform a conditional update
(insert a new attribute name-value pair if it doesn't exist,
or replace an existing name-value pair if it has certain
expected attribute values).
In addition to updating an item, you can also return the
item's attribute values in the same operation, using the
ReturnValues parameter.
:type table_name: string
:param table_name: The name of the table containing the item to update.
:type key: map
:param key: The primary key that defines the item. Each element
consists of an attribute name and a value for that attribute.
:type attribute_updates: map
:param attribute_updates: The names of attributes to be modified, the
action to perform on each, and the new value for each. If you are
updating an attribute that is an index key attribute for any
indexes on that table, the attribute type must match the index key
type defined in the AttributesDefinition of the table description.
You can use UpdateItem to update any non-key attributes.
Attribute values cannot be null. String and binary type attributes must
have lengths greater than zero. Set type attributes must not be
empty. Requests with empty values will be rejected with a
ValidationException .
Each AttributeUpdates element consists of an attribute name to modify,
along with the following:
+ Value - The new value, if applicable, for this attribute.
+ Action - Specifies how to perform the update. Valid values for Action
are `PUT`, `DELETE`, and `ADD`. The behavior depends on whether the
specified primary key already exists in the table. **If an item
with the specified Key is found in the table:**
+ `PUT` - Adds the specified attribute to the item. If the attribute
already exists, it is replaced by the new value.
+ `DELETE` - If no value is specified, the attribute and its value are
removed from the item. The data type of the specified value must
match the existing value's data type. If a set of values is
specified, then those values are subtracted from the old set. For
example, if the attribute value was the set `[a,b,c]` and the
DELETE action specified `[a,c]`, then the final attribute value
would be `[b]`. Specifying an empty set is an error.
+ `ADD` - If the attribute does not already exist, then the attribute
and its values are added to the item. If the attribute does exist,
then the behavior of `ADD` depends on the data type of the
attribute:
+ If the existing attribute is a number, and if Value is also a number,
then the Value is mathematically added to the existing attribute.
If Value is a negative number, then it is subtracted from the
existing attribute. If you use `ADD` to increment or decrement a
number value for an item that doesn't exist before the update,
Amazon DynamoDB uses 0 as the initial value. In addition, if you
use `ADD` to update an existing item, and intend to increment or
decrement an attribute value which does not yet exist, Amazon
DynamoDB uses `0` as the initial value. For example, suppose that
the item you want to update does not yet have an attribute named
itemcount , but you decide to `ADD` the number `3` to this
attribute anyway, even though it currently does not exist. Amazon
DynamoDB will create the itemcount attribute, set its initial value
to `0`, and finally add `3` to it. The result will be a new
itemcount attribute in the item, with a value of `3`.
+ If the existing data type is a set, and if the Value is also a set,
then the Value is added to the existing set. (This is a set
operation, not mathematical addition.) For example, if the
attribute value was the set `[1,2]`, and the `ADD` action specified
`[3]`, then the final attribute value would be `[1,2,3]`. An error
occurs if an Add action is specified for a set attribute and the
attribute type specified does not match the existing set type. Both
sets must have the same primitive data type. For example, if the
existing data type is a set of strings, the Value must also be a
set of strings. The same holds true for number sets and binary
sets.
This action is only valid for an existing attribute whose data type is
number or is a set. Do not use `ADD` for any other data types.
**If no item with the specified Key is found:**
+ `PUT` - Amazon DynamoDB creates a new item with the specified primary
key, and then adds the attribute.
+ `DELETE` - Nothing happens; there is no attribute to delete.
+ `ADD` - Amazon DynamoDB creates an item with the supplied primary key
and number (or set of numbers) for the attribute value. The only
data types allowed are number and number set; no other data types
can be specified.
If you specify any attributes that are part of an index key, then the
data types for those attributes must match those of the schema in
the table's attribute definition.
:type expected: map
:param expected: A map of attribute/condition pairs. This is the
conditional block for the UpdateItem operation. All the conditions
must be met for the operation to succeed.
Expected allows you to provide an attribute name, and whether or not
Amazon DynamoDB should check to see if the attribute value already
exists; or if the attribute value exists and has a particular value
before changing it.
Each item in Expected represents an attribute name for Amazon DynamoDB
to check, along with the following:
+ Value - The attribute value for Amazon DynamoDB to check.
+ Exists - Causes Amazon DynamoDB to evaluate the value before
attempting a conditional operation:
+ If Exists is `True`, Amazon DynamoDB will check to see if that
attribute value already exists in the table. If it is found, then
the operation succeeds. If it is not found, the operation fails
with a ConditionalCheckFailedException .
+ If Exists is `False`, Amazon DynamoDB assumes that the attribute
value does not exist in the table. If in fact the value does not
exist, then the assumption is valid and the operation succeeds. If
the value is found, despite the assumption that it does not exist,
the operation fails with a ConditionalCheckFailedException .
The default setting for Exists is `True`. If you supply a Value all by
itself, Amazon DynamoDB assumes the attribute exists: You don't
have to set Exists to `True`, because it is implied. Amazon
DynamoDB returns a ValidationException if:
+ Exists is `True` but there is no Value to check. (You expect a value
to exist, but don't specify what that value is.)
+ Exists is `False` but you also specify a Value . (You cannot expect
an attribute to have a value, while also expecting it not to
exist.)
If you specify more than one condition for Exists , then all of the
conditions must evaluate to true. (In other words, the conditions
are ANDed together.) Otherwise, the conditional operation will
fail.
:type return_values: string
:param return_values:
Use ReturnValues if you want to get the item attributes as they
appeared either before or after they were updated. For UpdateItem ,
the valid values are:
+ `NONE` - If ReturnValues is not specified, or if its value is `NONE`,
then nothing is returned. (This is the default for ReturnValues .)
+ `ALL_OLD` - If UpdateItem overwrote an attribute name-value pair,
then the content of the old item is returned.
+ `UPDATED_OLD` - The old versions of only the updated attributes are
returned.
+ `ALL_NEW` - All of the attributes of the new version of the item are
returned.
+ `UPDATED_NEW` - The new versions of only the updated attributes are
returned.
:type return_consumed_capacity: string
:param return_consumed_capacity:
:type return_item_collection_metrics: string
:param return_item_collection_metrics: If set to `SIZE`, statistics
about item collections, if any, that were modified during the
operation are returned in the response. If set to `NONE` (the
default), no statistics are returned..
"""
params = {'TableName': table_name, 'Key': key, }
if attribute_updates is not None:
params['AttributeUpdates'] = attribute_updates
if expected is not None:
params['Expected'] = expected
if return_values is not None:
params['ReturnValues'] = return_values
if return_consumed_capacity is not None:
params['ReturnConsumedCapacity'] = return_consumed_capacity
if return_item_collection_metrics is not None:
params['ReturnItemCollectionMetrics'] = return_item_collection_metrics
return self.make_request(action='UpdateItem',
body=json.dumps(params))
def update_table(self, table_name, provisioned_throughput):
"""
Updates the provisioned throughput for the given table.
Setting the throughput for a table helps you manage
performance and is part of the provisioned throughput feature
of Amazon DynamoDB.
The provisioned throughput values can be upgraded or
downgraded based on the maximums and minimums listed in the
`Limits`_ section in the Amazon DynamoDB Developer Guide .
The table must be in the `ACTIVE` state for this operation to
succeed. UpdateTable is an asynchronous operation; while
executing the operation, the table is in the `UPDATING` state.
While the table is in the `UPDATING` state, the table still
has the provisioned throughput from before the call. The new
provisioned throughput setting is in effect only when the
table returns to the `ACTIVE` state after the UpdateTable
operation.
You cannot add, modify or delete local secondary indexes using
UpdateTable . Local secondary indexes can only be defined at
table creation time.
:type table_name: string
:param table_name: The name of the table to be updated.
:type provisioned_throughput: dict
:param provisioned_throughput:
"""
params = {
'TableName': table_name,
'ProvisionedThroughput': provisioned_throughput,
}
return self.make_request(action='UpdateTable',
body=json.dumps(params))
def make_request(self, action, body):
headers = {
'X-Amz-Target': '%s.%s' % (self.TargetPrefix, action),
'Host': self.host,
'Content-Type': 'application/x-amz-json-1.0',
'Content-Length': str(len(body)),
}
http_request = self.build_base_http_request(
method='POST', path='/', auth_path='/', params={},
headers=headers, data=body, host=self.host)
response = self._mexe(http_request, sender=None,
override_num_retries=self.NumberRetries,
retry_handler=self._retry_handler)
response_body = response.read()
boto.log.debug(response_body)
if response.status == 200:
if response_body:
return json.loads(response_body)
else:
json_body = json.loads(response_body)
fault_name = json_body.get('__type', None)
exception_class = self._faults.get(fault_name, self.ResponseError)
raise exception_class(response.status, response.reason,
body=json_body)
def _retry_handler(self, response, i, next_sleep):
status = None
boto.log.debug("Saw HTTP status: %s" % response.status)
if response.status == 400:
response_body = response.read()
boto.log.debug(response_body)
data = json.loads(response_body)
if 'ProvisionedThroughputExceededException' in data.get('__type'):
self.throughput_exceeded_events += 1
msg = "%s, retry attempt %s" % (
'ProvisionedThroughputExceededException',
i
)
next_sleep = self._exponential_time(i)
i += 1
status = (msg, i, next_sleep)
if i == self.NumberRetries:
# If this was our last retry attempt, raise
# a specific error saying that the throughput
# was exceeded.
raise exceptions.ProvisionedThroughputExceededException(
response.status, response.reason, data)
elif 'ConditionalCheckFailedException' in data.get('__type'):
raise exceptions.ConditionalCheckFailedException(
response.status, response.reason, data)
elif 'ValidationException' in data.get('__type'):
raise exceptions.ValidationException(
response.status, response.reason, data)
else:
raise self.ResponseError(response.status, response.reason,
data)
expected_crc32 = response.getheader('x-amz-crc32')
if self._validate_checksums and expected_crc32 is not None:
boto.log.debug('Validating crc32 checksum for body: %s',
response.read())
actual_crc32 = crc32(response.read()) & 0xffffffff
expected_crc32 = int(expected_crc32)
if actual_crc32 != expected_crc32:
msg = ("The calculated checksum %s did not match the expected "
"checksum %s" % (actual_crc32, expected_crc32))
status = (msg, i + 1, self._exponential_time(i))
return status
def _exponential_time(self, i):
if i == 0:
next_sleep = 0
else:
next_sleep = 0.05 * (2 ** i)
return next_sleep
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