SimpleDB ******** Client ====== class SimpleDB.Client A low-level client representing Amazon SimpleDB Amazon SimpleDB is a web service providing the core database functions of data indexing and querying in the cloud. By offloading the time and effort associated with building and operating a web-scale database, SimpleDB provides developers the freedom to focus on application development. A traditional, clustered relational database requires a sizable upfront capital outlay, is complex to design, and often requires extensive and repetitive database administration. Amazon SimpleDB is dramatically simpler, requiring no schema, automatically indexing your data and providing a simple API for storage and access. This approach eliminates the administrative burden of data modeling, index maintenance, and performance tuning. Developers gain access to this functionality within Amazon's proven computing environment, are able to scale instantly, and pay only for what they use. Visit http://aws.amazon.com/simpledb/ for more information. import boto3 client = boto3.client('sdb') These are the available methods: * batch_delete_attributes * batch_put_attributes * can_paginate * close * create_domain * delete_attributes * delete_domain * domain_metadata * get_attributes * get_paginator * get_waiter * list_domains * put_attributes * select Paginators ========== Paginators are available on a client instance via the "get_paginator" method. For more detailed instructions and examples on the usage of paginators, see the paginators user guide. The available paginators are: * ListDomains * Select SimpleDB / Paginator / ListDomains ListDomains *********** class SimpleDB.Paginator.ListDomains paginator = client.get_paginator('list_domains') paginate(**kwargs) Creates an iterator that will paginate through responses from "SimpleDB.Client.list_domains()". See also: AWS API Documentation **Request Syntax** response_iterator = paginator.paginate( PaginationConfig={ 'MaxItems': 123, 'PageSize': 123, 'StartingToken': 'string' } ) Parameters: **PaginationConfig** (*dict*) -- A dictionary that provides parameters to control pagination. * **MaxItems** *(integer) --* The total number of items to return. If the total number of items available is more than the value specified in max- items then a "NextToken" will be provided in the output that you can use to resume pagination. * **PageSize** *(integer) --* The size of each page. * **StartingToken** *(string) --* A token to specify where to start paginating. This is the "NextToken" from a previous response. Return type: dict Returns: **Response Syntax** { 'DomainNames': [ 'string', ], } **Response Structure** * *(dict) --* * **DomainNames** *(list) --* A list of domain names that match the expression. * *(string) --* SimpleDB / Paginator / Select Select ****** class SimpleDB.Paginator.Select paginator = client.get_paginator('select') paginate(**kwargs) Creates an iterator that will paginate through responses from "SimpleDB.Client.select()". See also: AWS API Documentation **Request Syntax** response_iterator = paginator.paginate( SelectExpression='string', ConsistentRead=True|False, PaginationConfig={ 'MaxItems': 123, 'StartingToken': 'string' } ) Parameters: * **SelectExpression** (*string*) -- **[REQUIRED]** The expression used to query the domain. * **ConsistentRead** (*boolean*) -- Determines whether or not strong consistency should be enforced when data is read from SimpleDB. If "true", any data previously written to SimpleDB will be returned. Otherwise, results will be consistent eventually, and the client may not see data that was written immediately before your read. * **PaginationConfig** (*dict*) -- A dictionary that provides parameters to control pagination. * **MaxItems** *(integer) --* The total number of items to return. If the total number of items available is more than the value specified in max-items then a "NextToken" will be provided in the output that you can use to resume pagination. * **StartingToken** *(string) --* A token to specify where to start paginating. This is the "NextToken" from a previous response. Return type: dict Returns: **Response Syntax** { 'Items': [ { 'Name': 'string', 'AlternateNameEncoding': 'string', 'Attributes': [ { 'Name': 'string', 'AlternateNameEncoding': 'string', 'Value': 'string', 'AlternateValueEncoding': 'string' }, ] }, ], } **Response Structure** * *(dict) --* * **Items** *(list) --* A list of items that match the select expression. * *(dict) --* * **Name** *(string) --* The name of the item. * **AlternateNameEncoding** *(string) --* * **Attributes** *(list) --* A list of attributes. * *(dict) --* * **Name** *(string) --* The name of the attribute. * **AlternateNameEncoding** *(string) --* * **Value** *(string) --* The value of the attribute. * **AlternateValueEncoding** *(string) --* SimpleDB / Client / get_paginator get_paginator ************* SimpleDB.Client.get_paginator(operation_name) Create a paginator for an operation. Parameters: **operation_name** (*string*) -- The operation name. This is the same name as the method name on the client. For example, if the method name is "create_foo", and you'd normally invoke the operation as "client.create_foo(**kwargs)", if the "create_foo" operation can be paginated, you can use the call "client.get_paginator("create_foo")". Raises: **OperationNotPageableError** -- Raised if the operation is not pageable. You can use the "client.can_paginate" method to check if an operation is pageable. Return type: "botocore.paginate.Paginator" Returns: A paginator object. SimpleDB / Client / list_domains list_domains ************ SimpleDB.Client.list_domains(**kwargs) The "ListDomains" operation lists all domains associated with the Access Key ID. It returns domain names up to the limit set by MaxNumberOfDomains. A NextToken is returned if there are more than "MaxNumberOfDomains" domains. Calling "ListDomains" successive times with the "NextToken" provided by the operation returns up to "MaxNumberOfDomains" more domain names with each successive operation call. See also: AWS API Documentation **Request Syntax** response = client.list_domains( MaxNumberOfDomains=123, NextToken='string' ) Parameters: * **MaxNumberOfDomains** (*integer*) -- The maximum number of domain names you want returned. The range is 1 to 100. The default setting is 100. * **NextToken** (*string*) -- A string informing Amazon SimpleDB where to start the next list of domain names. Return type: dict Returns: **Response Syntax** { 'DomainNames': [ 'string', ], 'NextToken': 'string' } **Response Structure** * *(dict) --* * **DomainNames** *(list) --* A list of domain names that match the expression. * *(string) --* * **NextToken** *(string) --* An opaque token indicating that there are more domains than the specified "MaxNumberOfDomains" still available. **Exceptions** * "SimpleDB.Client.exceptions.InvalidParameterValue" * "SimpleDB.Client.exceptions.InvalidNextToken" SimpleDB / Client / batch_put_attributes batch_put_attributes ******************** SimpleDB.Client.batch_put_attributes(**kwargs) The "BatchPutAttributes" operation creates or replaces attributes within one or more items. By using this operation, the client can perform multiple PutAttribute operation with a single call. This helps yield savings in round trips and latencies, enabling Amazon SimpleDB to optimize requests and generally produce better throughput. The client may specify the item name with the "Item.X.ItemName" parameter. The client may specify new attributes using a combination of the "Item.X.Attribute.Y.Name" and "Item.X.Attribute.Y.Value" parameters. The client may specify the first attribute for the first item using the parameters "Item.0.Attribute.0.Name" and "Item.0.Attribute.0.Value", and for the second attribute for the first item by the parameters "Item.0.Attribute.1.Name" and "Item.0.Attribute.1.Value", and so on. Attributes are uniquely identified within an item by their name/value combination. For example, a single item can have the attributes "{ "first_name", "first_value" }" and "{ "first_name", "second_value" }". However, it cannot have two attribute instances where both the "Item.X.Attribute.Y.Name" and "Item.X.Attribute.Y.Value" are the same. Optionally, the requester can supply the "Replace" parameter for each individual value. Setting this value to "true" will cause the new attribute values to replace the existing attribute values. For example, if an item "I" has the attributes "{ 'a', '1' }, { 'b', '2'}" and "{ 'b', '3' }" and the requester does a BatchPutAttributes of "{'I', 'b', '4' }" with the Replace parameter set to true, the final attributes of the item will be "{ 'a', '1' }" and "{ 'b', '4' }", replacing the previous values of the 'b' attribute with the new value. Warning: This operation is vulnerable to exceeding the maximum URL size when making a REST request using the HTTP GET method. This operation does not support conditions using "Expected.X.Name", "Expected.X.Value", or "Expected.X.Exists". You can execute multiple "BatchPutAttributes" operations and other operations in parallel. However, large numbers of concurrent "BatchPutAttributes" calls can result in Service Unavailable (503) responses. The following limitations are enforced for this operation: * 256 attribute name-value pairs per item * 1 MB request size * 1 billion attributes per domain * 10 GB of total user data storage per domain * 25 item limit per "BatchPutAttributes" operation See also: AWS API Documentation **Request Syntax** response = client.batch_put_attributes( DomainName='string', Items=[ { 'Name': 'string', 'Attributes': [ { 'Name': 'string', 'Value': 'string', 'Replace': True|False }, ] }, ] ) Parameters: * **DomainName** (*string*) -- **[REQUIRED]** The name of the domain in which the attributes are being stored. * **Items** (*list*) -- **[REQUIRED]** A list of items on which to perform the operation. * *(dict) --* * **Name** *(string) --* **[REQUIRED]** The name of the replaceable item. * **Attributes** *(list) --* **[REQUIRED]** The list of attributes for a replaceable item. * *(dict) --* * **Name** *(string) --* **[REQUIRED]** The name of the replaceable attribute. * **Value** *(string) --* **[REQUIRED]** The value of the replaceable attribute. * **Replace** *(boolean) --* A flag specifying whether or not to replace the attribute/value pair or to add a new attribute/value pair. The default setting is "false". Returns: None **Exceptions** * "SimpleDB.Client.exceptions.DuplicateItemName" * "SimpleDB.Client.exceptions.InvalidParameterValue" * "SimpleDB.Client.exceptions.MissingParameter" * "SimpleDB.Client.exceptions.NoSuchDomain" * "SimpleDB.Client.exceptions.NumberItemAttributesExceeded" * "SimpleDB.Client.exceptions.NumberDomainAttributesExceeded" * "SimpleDB.Client.exceptions.NumberDomainBytesExceeded" * "SimpleDB.Client.exceptions.NumberSubmittedItemsExceeded" * "SimpleDB.Client.exceptions.NumberSubmittedAttributesExceeded" SimpleDB / Client / can_paginate can_paginate ************ SimpleDB.Client.can_paginate(operation_name) Check if an operation can be paginated. Parameters: **operation_name** (*string*) -- The operation name. This is the same name as the method name on the client. For example, if the method name is "create_foo", and you'd normally invoke the operation as "client.create_foo(**kwargs)", if the "create_foo" operation can be paginated, you can use the call "client.get_paginator("create_foo")". Returns: "True" if the operation can be paginated, "False" otherwise. SimpleDB / Client / domain_metadata domain_metadata *************** SimpleDB.Client.domain_metadata(**kwargs) Returns information about the domain, including when the domain was created, the number of items and attributes in the domain, and the size of the attribute names and values. See also: AWS API Documentation **Request Syntax** response = client.domain_metadata( DomainName='string' ) Parameters: **DomainName** (*string*) -- **[REQUIRED]** The name of the domain for which to display the metadata of. Return type: dict Returns: **Response Syntax** { 'ItemCount': 123, 'ItemNamesSizeBytes': 123, 'AttributeNameCount': 123, 'AttributeNamesSizeBytes': 123, 'AttributeValueCount': 123, 'AttributeValuesSizeBytes': 123, 'Timestamp': 123 } **Response Structure** * *(dict) --* * **ItemCount** *(integer) --* The number of all items in the domain. * **ItemNamesSizeBytes** *(integer) --* The total size of all item names in the domain, in bytes. * **AttributeNameCount** *(integer) --* The number of unique attribute names in the domain. * **AttributeNamesSizeBytes** *(integer) --* The total size of all unique attribute names in the domain, in bytes. * **AttributeValueCount** *(integer) --* The number of all attribute name/value pairs in the domain. * **AttributeValuesSizeBytes** *(integer) --* The total size of all attribute values in the domain, in bytes. * **Timestamp** *(integer) --* The data and time when metadata was calculated, in Epoch (UNIX) seconds. **Exceptions** * "SimpleDB.Client.exceptions.MissingParameter" * "SimpleDB.Client.exceptions.NoSuchDomain" SimpleDB / Client / get_attributes get_attributes ************** SimpleDB.Client.get_attributes(**kwargs) Returns all of the attributes associated with the specified item. Optionally, the attributes returned can be limited to one or more attributes by specifying an attribute name parameter. If the item does not exist on the replica that was accessed for this operation, an empty set is returned. The system does not return an error as it cannot guarantee the item does not exist on other replicas. See also: AWS API Documentation **Request Syntax** response = client.get_attributes( DomainName='string', ItemName='string', AttributeNames=[ 'string', ], ConsistentRead=True|False ) Parameters: * **DomainName** (*string*) -- **[REQUIRED]** The name of the domain in which to perform the operation. * **ItemName** (*string*) -- **[REQUIRED]** The name of the item. * **AttributeNames** (*list*) -- The names of the attributes. * *(string) --* * **ConsistentRead** (*boolean*) -- Determines whether or not strong consistency should be enforced when data is read from SimpleDB. If "true", any data previously written to SimpleDB will be returned. Otherwise, results will be consistent eventually, and the client may not see data that was written immediately before your read. Return type: dict Returns: **Response Syntax** { 'Attributes': [ { 'Name': 'string', 'AlternateNameEncoding': 'string', 'Value': 'string', 'AlternateValueEncoding': 'string' }, ] } **Response Structure** * *(dict) --* * **Attributes** *(list) --* The list of attributes returned by the operation. * *(dict) --* * **Name** *(string) --* The name of the attribute. * **AlternateNameEncoding** *(string) --* * **Value** *(string) --* The value of the attribute. * **AlternateValueEncoding** *(string) --* **Exceptions** * "SimpleDB.Client.exceptions.InvalidParameterValue" * "SimpleDB.Client.exceptions.MissingParameter" * "SimpleDB.Client.exceptions.NoSuchDomain" SimpleDB / Client / create_domain create_domain ************* SimpleDB.Client.create_domain(**kwargs) The "CreateDomain" operation creates a new domain. The domain name should be unique among the domains associated with the Access Key ID provided in the request. The "CreateDomain" operation may take 10 or more seconds to complete. The client can create up to 100 domains per account. If the client requires additional domains, go to http://aws.amazon.com/contact-us/simpledb-limit-request/. See also: AWS API Documentation **Request Syntax** response = client.create_domain( DomainName='string' ) Parameters: **DomainName** (*string*) -- **[REQUIRED]** The name of the domain to create. The name can range between 3 and 255 characters and can contain the following characters: a-z, A-Z, 0-9, '_', '-', and '.'. Returns: None **Exceptions** * "SimpleDB.Client.exceptions.InvalidParameterValue" * "SimpleDB.Client.exceptions.MissingParameter" * "SimpleDB.Client.exceptions.NumberDomainsExceeded" SimpleDB / Client / delete_domain delete_domain ************* SimpleDB.Client.delete_domain(**kwargs) The "DeleteDomain" operation deletes a domain. Any items (and their attributes) in the domain are deleted as well. The "DeleteDomain" operation might take 10 or more seconds to complete. See also: AWS API Documentation **Request Syntax** response = client.delete_domain( DomainName='string' ) Parameters: **DomainName** (*string*) -- **[REQUIRED]** The name of the domain to delete. Returns: None **Exceptions** * "SimpleDB.Client.exceptions.MissingParameter" SimpleDB / Client / put_attributes put_attributes ************** SimpleDB.Client.put_attributes(**kwargs) The PutAttributes operation creates or replaces attributes in an item. The client may specify new attributes using a combination of the "Attribute.X.Name" and "Attribute.X.Value" parameters. The client specifies the first attribute by the parameters "Attribute.0.Name" and "Attribute.0.Value", the second attribute by the parameters "Attribute.1.Name" and "Attribute.1.Value", and so on. Attributes are uniquely identified in an item by their name/value combination. For example, a single item can have the attributes "{ "first_name", "first_value" }" and "{ "first_name", second_value" }". However, it cannot have two attribute instances where both the "Attribute.X.Name" and "Attribute.X.Value" are the same. Optionally, the requestor can supply the "Replace" parameter for each individual attribute. Setting this value to "true" causes the new attribute value to replace the existing attribute value(s). For example, if an item has the attributes "{ 'a', '1' }", "{ 'b', '2'}" and "{ 'b', '3' }" and the requestor calls "PutAttributes" using the attributes "{ 'b', '4' }" with the "Replace" parameter set to true, the final attributes of the item are changed to "{ 'a', '1' }" and "{ 'b', '4' }", which replaces the previous values of the 'b' attribute with the new value. You cannot specify an empty string as an attribute name. Because Amazon SimpleDB makes multiple copies of client data and uses an eventual consistency update model, an immediate GetAttributes or Select operation (read) immediately after a PutAttributes or DeleteAttributes operation (write) might not return the updated data. The following limitations are enforced for this operation: * 256 total attribute name-value pairs per item * One billion attributes per domain * 10 GB of total user data storage per domain See also: AWS API Documentation **Request Syntax** response = client.put_attributes( DomainName='string', ItemName='string', Attributes=[ { 'Name': 'string', 'Value': 'string', 'Replace': True|False }, ], Expected={ 'Name': 'string', 'Value': 'string', 'Exists': True|False } ) Parameters: * **DomainName** (*string*) -- **[REQUIRED]** The name of the domain in which to perform the operation. * **ItemName** (*string*) -- **[REQUIRED]** The name of the item. * **Attributes** (*list*) -- **[REQUIRED]** The list of attributes. * *(dict) --* * **Name** *(string) --* **[REQUIRED]** The name of the replaceable attribute. * **Value** *(string) --* **[REQUIRED]** The value of the replaceable attribute. * **Replace** *(boolean) --* A flag specifying whether or not to replace the attribute/value pair or to add a new attribute/value pair. The default setting is "false". * **Expected** (*dict*) -- The update condition which, if specified, determines whether the specified attributes will be updated or not. The update condition must be satisfied in order for this request to be processed and the attributes to be updated. * **Name** *(string) --* The name of the attribute involved in the condition. * **Value** *(string) --* The value of an attribute. This value can only be specified when the "Exists" parameter is equal to "true". * **Exists** *(boolean) --* A value specifying whether or not the specified attribute must exist with the specified value in order for the update condition to be satisfied. Specify "true" if the attribute must exist for the update condition to be satisfied. Specify "false" if the attribute should not exist in order for the update condition to be satisfied. Returns: None **Exceptions** * "SimpleDB.Client.exceptions.InvalidParameterValue" * "SimpleDB.Client.exceptions.MissingParameter" * "SimpleDB.Client.exceptions.NoSuchDomain" * "SimpleDB.Client.exceptions.NumberDomainAttributesExceeded" * "SimpleDB.Client.exceptions.NumberDomainBytesExceeded" * "SimpleDB.Client.exceptions.NumberItemAttributesExceeded" * "SimpleDB.Client.exceptions.AttributeDoesNotExist" SimpleDB / Client / get_waiter get_waiter ********** SimpleDB.Client.get_waiter(waiter_name) Returns an object that can wait for some condition. Parameters: **waiter_name** (*str*) -- The name of the waiter to get. See the waiters section of the service docs for a list of available waiters. Returns: The specified waiter object. Return type: "botocore.waiter.Waiter" SimpleDB / Client / select select ****** SimpleDB.Client.select(**kwargs) The "Select" operation returns a set of attributes for "ItemNames" that match the select expression. "Select" is similar to the standard SQL SELECT statement. The total size of the response cannot exceed 1 MB in total size. Amazon SimpleDB automatically adjusts the number of items returned per page to enforce this limit. For example, if the client asks to retrieve 2500 items, but each individual item is 10 kB in size, the system returns 100 items and an appropriate "NextToken" so the client can access the next page of results. For information on how to construct select expressions, see Using Select to Create Amazon SimpleDB Queries in the Developer Guide. See also: AWS API Documentation **Request Syntax** response = client.select( SelectExpression='string', NextToken='string', ConsistentRead=True|False ) Parameters: * **SelectExpression** (*string*) -- **[REQUIRED]** The expression used to query the domain. * **NextToken** (*string*) -- A string informing Amazon SimpleDB where to start the next list of "ItemNames". * **ConsistentRead** (*boolean*) -- Determines whether or not strong consistency should be enforced when data is read from SimpleDB. If "true", any data previously written to SimpleDB will be returned. Otherwise, results will be consistent eventually, and the client may not see data that was written immediately before your read. Return type: dict Returns: **Response Syntax** { 'Items': [ { 'Name': 'string', 'AlternateNameEncoding': 'string', 'Attributes': [ { 'Name': 'string', 'AlternateNameEncoding': 'string', 'Value': 'string', 'AlternateValueEncoding': 'string' }, ] }, ], 'NextToken': 'string' } **Response Structure** * *(dict) --* * **Items** *(list) --* A list of items that match the select expression. * *(dict) --* * **Name** *(string) --* The name of the item. * **AlternateNameEncoding** *(string) --* * **Attributes** *(list) --* A list of attributes. * *(dict) --* * **Name** *(string) --* The name of the attribute. * **AlternateNameEncoding** *(string) --* * **Value** *(string) --* The value of the attribute. * **AlternateValueEncoding** *(string) --* * **NextToken** *(string) --* An opaque token indicating that more items than "MaxNumberOfItems" were matched, the response size exceeded 1 megabyte, or the execution time exceeded 5 seconds. **Exceptions** * "SimpleDB.Client.exceptions.InvalidParameterValue" * "SimpleDB.Client.exceptions.InvalidNextToken" * "SimpleDB.Client.exceptions.InvalidNumberPredicates" * "SimpleDB.Client.exceptions.InvalidNumberValueTests" * "SimpleDB.Client.exceptions.InvalidQueryExpression" * "SimpleDB.Client.exceptions.MissingParameter" * "SimpleDB.Client.exceptions.NoSuchDomain" * "SimpleDB.Client.exceptions.RequestTimeout" * "SimpleDB.Client.exceptions.TooManyRequestedAttributes" SimpleDB / Client / batch_delete_attributes batch_delete_attributes *********************** SimpleDB.Client.batch_delete_attributes(**kwargs) Performs multiple DeleteAttributes operations in a single call, which reduces round trips and latencies. This enables Amazon SimpleDB to optimize requests, which generally yields better throughput. The following limitations are enforced for this operation: * 1 MB request size * 25 item limit per BatchDeleteAttributes operation See also: AWS API Documentation **Request Syntax** response = client.batch_delete_attributes( DomainName='string', Items=[ { 'Name': 'string', 'Attributes': [ { 'Name': 'string', 'AlternateNameEncoding': 'string', 'Value': 'string', 'AlternateValueEncoding': 'string' }, ] }, ] ) Parameters: * **DomainName** (*string*) -- **[REQUIRED]** The name of the domain in which the attributes are being deleted. * **Items** (*list*) -- **[REQUIRED]** A list of items on which to perform the operation. * *(dict) --* * **Name** *(string) --* **[REQUIRED]** * **Attributes** *(list) --* * *(dict) --* * **Name** *(string) --* **[REQUIRED]** The name of the attribute. * **AlternateNameEncoding** *(string) --* * **Value** *(string) --* **[REQUIRED]** The value of the attribute. * **AlternateValueEncoding** *(string) --* Returns: None SimpleDB / Client / close close ***** SimpleDB.Client.close() Closes underlying endpoint connections. SimpleDB / Client / delete_attributes delete_attributes ***************** SimpleDB.Client.delete_attributes(**kwargs) Deletes one or more attributes associated with an item. If all attributes of the item are deleted, the item is deleted. "DeleteAttributes" is an idempotent operation; running it multiple times on the same item or attribute does not result in an error response. Because Amazon SimpleDB makes multiple copies of item data and uses an eventual consistency update model, performing a GetAttributes or Select operation (read) immediately after a "DeleteAttributes" or PutAttributes operation (write) might not return updated item data. See also: AWS API Documentation **Request Syntax** response = client.delete_attributes( DomainName='string', ItemName='string', Attributes=[ { 'Name': 'string', 'AlternateNameEncoding': 'string', 'Value': 'string', 'AlternateValueEncoding': 'string' }, ], Expected={ 'Name': 'string', 'Value': 'string', 'Exists': True|False } ) Parameters: * **DomainName** (*string*) -- **[REQUIRED]** The name of the domain in which to perform the operation. * **ItemName** (*string*) -- **[REQUIRED]** The name of the item. Similar to rows on a spreadsheet, items represent individual objects that contain one or more value-attribute pairs. * **Attributes** (*list*) -- A list of Attributes. Similar to columns on a spreadsheet, attributes represent categories of data that can be assigned to items. * *(dict) --* * **Name** *(string) --* **[REQUIRED]** The name of the attribute. * **AlternateNameEncoding** *(string) --* * **Value** *(string) --* **[REQUIRED]** The value of the attribute. * **AlternateValueEncoding** *(string) --* * **Expected** (*dict*) -- The update condition which, if specified, determines whether the specified attributes will be deleted or not. The update condition must be satisfied in order for this request to be processed and the attributes to be deleted. * **Name** *(string) --* The name of the attribute involved in the condition. * **Value** *(string) --* The value of an attribute. This value can only be specified when the "Exists" parameter is equal to "true". * **Exists** *(boolean) --* A value specifying whether or not the specified attribute must exist with the specified value in order for the update condition to be satisfied. Specify "true" if the attribute must exist for the update condition to be satisfied. Specify "false" if the attribute should not exist in order for the update condition to be satisfied. Returns: None **Exceptions** * "SimpleDB.Client.exceptions.InvalidParameterValue" * "SimpleDB.Client.exceptions.MissingParameter" * "SimpleDB.Client.exceptions.NoSuchDomain" * "SimpleDB.Client.exceptions.AttributeDoesNotExist"