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Amazon DynamoDB

Amazon DynamoDB is a fully managed NoSQL database service that provides fast and predictable performance with seamless scalability. DynamoDB lets you offload the administrative burdens of operating and scaling a distributed database, so that you don't have to worry about hardware provisioning, setup and configuration, replication, software patching, or cluster scaling.

With DynamoDB, you can create database tables that can store and retrieve any amount of data, and serve any level of request traffic. You can scale up or scale down your tables' throughput capacity without downtime or performance degradation, and use the Amazon Web Services Management Console to monitor resource utilization and performance metrics.

DynamoDB automatically spreads the data and traffic for your tables over a sufficient number of servers to handle your throughput and storage requirements, while maintaining consistent and fast performance. All of your data is stored on solid state disks (SSDs) and automatically replicated across multiple Availability Zones in an Amazon Web Services Region, providing built-in high availability and data durability.

Hierarchy

Constructors

Properties

The resolved configuration of DynamoDBClient class. This is resolved and normalized from the constructor configuration interface.

middlewareStack: MiddlewareStack<ServiceInputTypes, ServiceOutputTypes>

Methods

  • 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 16 MB of data, which can contain as many as 100 items. BatchGetItem returns 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.

    If you request more than 100 items, BatchGetItem returns a ValidationException with the message "Too many items requested for the BatchGetItem call."

    For example, if you ask to retrieve 100 items, but each individual item is 300 KB in size, the system returns 52 items (so as not to exceed the 16 MB limit). It also returns 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 none of the items can be processed due to insufficient provisioned throughput on all of the tables in the request, then BatchGetItem returns a ProvisionedThroughputExceededException. If at least one of the items is successfully processed, then BatchGetItem completes successfully, while returning the keys of the unread items in UnprocessedKeys.

    If DynamoDB returns any unprocessed items, you should retry the batch operation on those items. However, we strongly recommend that you use an exponential backoff algorithm. If you retry the batch operation immediately, the underlying read or write requests can still fail due to throttling on the individual tables. If you delay the batch operation using exponential backoff, the individual requests in the batch are much more likely to succeed.

    For more information, see Batch Operations and Error Handling in the Amazon DynamoDB Developer Guide.

    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 retrieves items in parallel.

    When designing your application, keep in mind that DynamoDB does not return items in any particular order. To help parse the response by item, include the primary key values for the items in your request in the ProjectionExpression 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 Working with Tables in the Amazon DynamoDB Developer Guide.

    Parameters

    Returns Promise<BatchGetItemCommandOutput>

  • Parameters

    Returns void

  • Parameters

    Returns void

  • The BatchWriteItem operation puts or deletes multiple items in one or more tables. A single call to BatchWriteItem can transmit up to 16MB of data over the network, consisting of up to 25 item put or delete operations. While individual items can be up to 400 KB once stored, it's important to note that an item's representation might be greater than 400KB while being sent in DynamoDB's JSON format for the API call. For more details on this distinction, see Naming Rules and Data Types.

    BatchWriteItem cannot update items. If you perform a BatchWriteItem operation on an existing item, that item's values will be overwritten by the operation and it will appear like it was updated. To update items, we recommend you use the UpdateItem action.

    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.

    If none of the items can be processed due to insufficient provisioned throughput on all of the tables in the request, then BatchWriteItem returns a ProvisionedThroughputExceededException.

    If DynamoDB returns any unprocessed items, you should retry the batch operation on those items. However, we strongly recommend that you use an exponential backoff algorithm. If you retry the batch operation immediately, the underlying read or write requests can still fail due to throttling on the individual tables. If you delay the batch operation using exponential backoff, the individual requests in the batch are much more likely to succeed.

    For more information, see Batch Operations and Error Handling in the Amazon DynamoDB Developer Guide.

    With BatchWriteItem, you can efficiently write or delete large amounts of data, such as from Amazon EMR, or copy data from another database into 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, 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, you must update or delete the specified items one at a time. In both situations, BatchWriteItem 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, 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.

    • Your request contains at least two items with identical hash and range keys (which essentially is two put operations).

    • There are more than 25 requests in the batch.

    • Any individual item in a batch exceeds 400 KB.

    • The total request size exceeds 16 MB.

    Parameters

    Returns Promise<BatchWriteItemCommandOutput>

  • Parameters

    Returns void

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    Returns void

  • Returns the current provisioned-capacity quotas for your Amazon Web Services account in a Region, both for the Region as a whole and for any one DynamoDB table that you create there.

    When you establish an Amazon Web Services account, the account has initial quotas on the maximum read capacity units and write capacity units that you can provision across all of your DynamoDB tables in a given Region. Also, there are per-table quotas that apply when you create a table there. For more information, see Service, Account, and Table Quotas page in the Amazon DynamoDB Developer Guide.

    Although you can increase these quotas by filing a case at Amazon Web Services Support Center, obtaining the increase is not instantaneous. The DescribeLimits action lets you write code to compare the capacity you are currently using to those quotas imposed by your account so that you have enough time to apply for an increase before you hit a quota.

    For example, you could use one of the Amazon Web Services SDKs to do the following:

    1. Call DescribeLimits for a particular Region to obtain your current account quotas on provisioned capacity there.

    2. Create a variable to hold the aggregate read capacity units provisioned for all your tables in that Region, and one to hold the aggregate write capacity units. Zero them both.

    3. Call ListTables to obtain a list of all your DynamoDB tables.

    4. For each table name listed by ListTables, do the following:

      • Call DescribeTable with the table name.

      • Use the data returned by DescribeTable to add the read capacity units and write capacity units provisioned for the table itself to your variables.

      • If the table has one or more global secondary indexes (GSIs), loop over these GSIs and add their provisioned capacity values to your variables as well.

    5. Report the account quotas for that Region returned by DescribeLimits, along with the total current provisioned capacity levels you have calculated.

    This will let you see whether you are getting close to your account-level quotas.

    The per-table quotas apply only when you are creating a new table. They restrict the sum of the provisioned capacity of the new table itself and all its global secondary indexes.

    For existing tables and their GSIs, DynamoDB doesn't let you increase provisioned capacity extremely rapidly, but the only quota that applies is that the aggregate provisioned capacity over all your tables and GSIs cannot exceed either of the per-account quotas.

    DescribeLimits should only be called periodically. You can expect throttling errors if you call it more than once in a minute.

    The DescribeLimits Request element has no content.

    Parameters

    Returns Promise<DescribeLimitsCommandOutput>

  • Parameters

    Returns void

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    Returns void

  • You must provide the name of the partition key attribute and a single value for that attribute. Query returns all items with that partition key value. Optionally, you can provide a sort key attribute and use a comparison operator to refine the search results.

    Use the KeyConditionExpression parameter to provide a specific value for the partition key. The Query operation will return all of the items from the table or index with that partition key value. You can optionally narrow the scope of the Query operation by specifying a sort key value and a comparison operator in KeyConditionExpression. To further refine the Query results, you can optionally provide a FilterExpression. A FilterExpression determines which items within the results should be returned to you. All of the other results are discarded.

    A Query operation always returns a result set. If no matching items are found, the result set will be empty. Queries that do not return results consume the minimum number of read capacity units for that type of read operation.

    DynamoDB calculates the number of read capacity units consumed based on item size, not on the amount of data that is returned to an application. The number of capacity units consumed will be the same whether you request all of the attributes (the default behavior) or just some of them (using a projection expression). The number will also be the same whether or not you use a FilterExpression.

    Query results are always sorted by the sort key value. If the data type of the sort key is Number, the results are returned in numeric order; otherwise, the results are returned in order of UTF-8 bytes. By default, the sort order is ascending. To reverse the order, set the ScanIndexForward parameter to false.

    A single Query operation will read up to the maximum number of items set (if using the Limit parameter) or a maximum of 1 MB of data and then apply any filtering to the results using FilterExpression. If LastEvaluatedKey is present in the response, you will need to paginate the result set. For more information, see Paginating the Results in the Amazon DynamoDB Developer Guide.

    FilterExpression is applied after a Query finishes, but before the results are returned. A FilterExpression cannot contain partition key or sort key attributes. You need to specify those attributes in the KeyConditionExpression.

    A Query operation can return an empty result set and a LastEvaluatedKey if all the items read for the page of results are filtered out.

    You can query a table, a local secondary index, or a global secondary index. For a query on a table or on a local secondary index, you can set the ConsistentRead parameter to true and obtain a strongly consistent result. Global secondary indexes support eventually consistent reads only, so do not specify ConsistentRead when querying a global secondary index.

    Parameters

    Returns Promise<QueryCommandOutput>

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    Returns void

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    Returns void

  • The Scan operation returns one or more items and item attributes by accessing every item in a table or a secondary index. To have DynamoDB return fewer items, you can provide a FilterExpression operation.

    If the total number of scanned items exceeds the maximum dataset size limit of 1 MB, the scan stops and results are returned to the user as a LastEvaluatedKey value 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.

    A single Scan operation reads up to the maximum number of items set (if using the Limit parameter) or a maximum of 1 MB of data and then apply any filtering to the results using FilterExpression. If LastEvaluatedKey is present in the response, you need to paginate the result set. For more information, see Paginating the Results in the Amazon DynamoDB Developer Guide.

    Scan operations proceed sequentially; however, for faster performance on a large table or secondary index, applications can request a parallel Scan operation by providing the Segment and TotalSegments parameters. For more information, see Parallel Scan in the Amazon DynamoDB Developer Guide.

    Scan uses eventually consistent reads when accessing the data in a table; therefore, the result set might not include the changes to data in the table immediately before the operation began. If you need a consistent copy of the data, as of the time that the Scan begins, you can set the ConsistentRead parameter to true.

    Parameters

    Returns Promise<ScanCommandOutput>

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    Returns void

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  • Type Parameters

    Parameters

    Returns Promise<OutputType>

  • Type Parameters

    Parameters

    • command: Command<ServiceInputTypes, InputType, ServiceOutputTypes, OutputType, SmithyResolvedConfiguration<HttpHandlerOptions>>
    • cb: ((err: any, data?: OutputType) => void)
        • (err: any, data?: OutputType): void
        • Parameters

          • err: any
          • Optional data: OutputType

          Returns void

    Returns void

  • Type Parameters

    Parameters

    • command: Command<ServiceInputTypes, InputType, ServiceOutputTypes, OutputType, SmithyResolvedConfiguration<HttpHandlerOptions>>
    • options: HttpHandlerOptions
    • cb: ((err: any, data?: OutputType) => void)
        • (err: any, data?: OutputType): void
        • Parameters

          • err: any
          • Optional data: OutputType

          Returns void

    Returns void

  • TransactWriteItems is a synchronous write operation that groups up to 100 action requests. These actions can target items in different tables, but not in different Amazon Web Services accounts or Regions, and no two actions can target the same item. For example, you cannot both ConditionCheck and Update the same item. The aggregate size of the items in the transaction cannot exceed 4 MB.

    The actions are completed atomically so that either all of them succeed, or all of them fail. They are defined by the following objects:

    • Put  —   Initiates a PutItem operation to write a new item. This structure specifies the primary key of the item to be written, the name of the table to write it in, an optional condition expression that must be satisfied for the write to succeed, a list of the item's attributes, and a field indicating whether to retrieve the item's attributes if the condition is not met.

    • Update  —   Initiates an UpdateItem operation to update an existing item. This structure specifies the primary key of the item to be updated, the name of the table where it resides, an optional condition expression that must be satisfied for the update to succeed, an expression that defines one or more attributes to be updated, and a field indicating whether to retrieve the item's attributes if the condition is not met.

    • Delete  —   Initiates a DeleteItem operation to delete an existing item. This structure specifies the primary key of the item to be deleted, the name of the table where it resides, an optional condition expression that must be satisfied for the deletion to succeed, and a field indicating whether to retrieve the item's attributes if the condition is not met.

    • ConditionCheck  —   Applies a condition to an item that is not being modified by the transaction. This structure specifies the primary key of the item to be checked, the name of the table where it resides, a condition expression that must be satisfied for the transaction to succeed, and a field indicating whether to retrieve the item's attributes if the condition is not met.

    DynamoDB rejects the entire TransactWriteItems request if any of the following is true:

    • A condition in one of the condition expressions is not met.

    • An ongoing operation is in the process of updating the same item.

    • There is insufficient provisioned capacity for the transaction to be completed.

    • An item size becomes too large (bigger than 400 KB), a local secondary index (LSI) becomes too large, or a similar validation error occurs because of changes made by the transaction.

    • The aggregate size of the items in the transaction exceeds 4 MB.

    • There is a user error, such as an invalid data format.

    Parameters

    Returns Promise<TransactWriteItemsCommandOutput>

  • Parameters

    Returns void

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    Returns void