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Class: Aws::DynamoDB::Resource

Inherits:
Resources::Resource show all
Defined in:
(unknown)

Overview

This class provides a resource oriented interface for DynamoDB. To create a resource object:

resource = Aws::DynamoDB::Resource.new

You can supply a client object with custom configuration that will be used for all resource operations. If you do not pass :client, a default client will be constructed.

client = Aws::DynamoDB::Client.new(region: 'us-west-2')
resource = Aws::DynamoDB::Resource.new(client: client)

Resource Resource Classes

Aws::DynamoDB::Resource has the following resource classes:

Instance Attribute Summary

Attributes inherited from Resources::Resource

#client, #identifiers

Instance Method Summary collapse

Methods inherited from Resources::Resource

add_data_attribute, add_identifier, #data, data_attributes, #data_loaded?, identifiers, #load, #wait_until

Methods included from Resources::OperationMethods

#add_batch_operation, #add_operation, #batch_operation, #batch_operation_names, #batch_operations, #operation, #operation_names, #operations

Constructor Details

#initialize(options = {}) ⇒ Object #initialize(options = {}) ⇒ Object

Overloads:

  • #initialize(options = {}) ⇒ Object

    Options Hash (options):

    • :client (Client)

      When `:client is not given, the options hash is used to construct a new Client object.

  • #initialize(options = {}) ⇒ Object

    Options Hash (options):

    • :client (Client)

      When `:client is not given, the options hash is used to construct a new Client object.

Instance Method Details

#batch_get_item(options = {}) ⇒ Types::BatchGetItemOutput

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 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.

If you request more than 100 items BatchGetItem will return 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 data set.

If none of the items can be processed due to insufficient provisioned throughput on all of the tables in the request, then BatchGetItem will return 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 Capacity Units Calculations in the Amazon DynamoDB Developer Guide.

Examples:

Request syntax example with placeholder values


dynamodb.batch_get_item({
  request_items: { # required
    "TableName" => {
      keys: [ # required
        {
          "AttributeName" => "value", # value <Hash,Array,String,Numeric,Boolean,IO,Set,nil>
        },
      ],
      attributes_to_get: ["AttributeName"],
      consistent_read: false,
      projection_expression: "ProjectionExpression",
      expression_attribute_names: {
        "ExpressionAttributeNameVariable" => "AttributeName",
      },
    },
  },
  return_consumed_capacity: "INDEXES", # accepts INDEXES, TOTAL, NONE
})

Options Hash (options):

  • :request_items (required, Hash<String,Types::KeysAndAttributes>)

    A map of one or more table names and, for each table, a map that describes one or more items to retrieve from that table. Each table name can be used only once per BatchGetItem request.

    Each element in the map of items to retrieve consists of the following:

    • ConsistentRead - If true, a strongly consistent read is used; if false (the default), an eventually consistent read is used.

    • ExpressionAttributeNames - One or more substitution tokens for attribute names in the ProjectionExpression parameter. The following are some use cases for using ExpressionAttributeNames:

      • To access an attribute whose name conflicts with a DynamoDB reserved word.

      • To create a placeholder for repeating occurrences of an attribute name in an expression.

      • To prevent special characters in an attribute name from being misinterpreted in an expression.

      Use the # character in an expression to dereference an attribute name. For example, consider the following attribute name:

      • Percentile

      ^

      The name of this attribute conflicts with a reserved word, so it cannot be used directly in an expression. (For the complete list of reserved words, see Reserved Words in the Amazon DynamoDB Developer Guide). To work around this, you could specify the following for ExpressionAttributeNames:

      • `{"#P":"Percentile"}`

      ^

      You could then use this substitution in an expression, as in this example:

      • #P = :val

      ^

      Tokens that begin with the : character are expression attribute values, which are placeholders for the actual value at runtime.

      For more information on expression attribute names, see Accessing Item Attributes in the Amazon DynamoDB Developer Guide.

    • Keys - An array of primary key attribute values that define specific items in the table. For each primary key, you must provide all of the key attributes. For example, with a simple primary key, you only need to provide the partition key value. For a composite key, you must provide both the partition key value and the sort key value.

    • ProjectionExpression - A string that identifies one or more attributes to retrieve from the table. These attributes can include scalars, sets, or elements of a JSON document. The attributes in the expression must be separated by commas.

      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.

      For more information, see Accessing Item Attributes in the Amazon DynamoDB Developer Guide.

    • AttributesToGet - This is a legacy parameter. Use ProjectionExpression instead. For more information, see AttributesToGet in the Amazon DynamoDB Developer Guide.

  • :return_consumed_capacity (String)

    Determines the level of detail about provisioned throughput consumption that is returned in the response:

    • INDEXES - The response includes the aggregate ConsumedCapacity for the operation, together with ConsumedCapacity for each table and secondary index that was accessed.

      Note that some operations, such as GetItem and BatchGetItem, do not access any indexes at all. In these cases, specifying INDEXES will only return ConsumedCapacity information for table(s).

    • TOTAL - The response includes only the aggregate ConsumedCapacity for the operation.

    • NONE - No ConsumedCapacity details are included in the response.

Returns:

See Also:

#batch_write_item(options = {}) ⇒ Types::BatchWriteItemOutput

The BatchWriteItem operation puts or deletes multiple items in one or more tables. A single call to BatchWriteItem can write up to 16 MB of data, which can comprise as many as 25 put or delete requests. Individual items to be written can be as large as 400 KB.

BatchWriteItem cannot update items. To update items, 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.

Note that if none of the items can be processed due to insufficient provisioned throughput on all of the tables in the request, then BatchWriteItem will return 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 Elastic MapReduce (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.

  • 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.

Examples:

Request syntax example with placeholder values


dynamodb.batch_write_item({
  request_items: { # required
    "TableName" => [
      {
        put_request: {
          item: { # required
            "AttributeName" => "value", # value <Hash,Array,String,Numeric,Boolean,IO,Set,nil>
          },
        },
        delete_request: {
          key: { # required
            "AttributeName" => "value", # value <Hash,Array,String,Numeric,Boolean,IO,Set,nil>
          },
        },
      },
    ],
  },
  return_consumed_capacity: "INDEXES", # accepts INDEXES, TOTAL, NONE
  return_item_collection_metrics: "SIZE", # accepts SIZE, NONE
})

Options Hash (options):

  • :request_items (required, Hash<String,Array<Types::WriteRequest>>)

    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. For each primary key, you must provide all of the key attributes. For example, with a simple primary key, you only need to provide a value for the partition key. For a composite primary key, you must provide values for both the partition key and the sort key.

      ^

    • 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 exception.

        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.

  • :return_consumed_capacity (String)

    Determines the level of detail about provisioned throughput consumption that is returned in the response:

    • INDEXES - The response includes the aggregate ConsumedCapacity for the operation, together with ConsumedCapacity for each table and secondary index that was accessed.

      Note that some operations, such as GetItem and BatchGetItem, do not access any indexes at all. In these cases, specifying INDEXES will only return ConsumedCapacity information for table(s).

    • TOTAL - The response includes only the aggregate ConsumedCapacity for the operation.

    • NONE - No ConsumedCapacity details are included in the response.

  • :return_item_collection_metrics (String)

    Determines whether item collection metrics are returned. If set to SIZE, the response includes 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.

Returns:

See Also:

#create_table(options = {}) ⇒ Table

Examples:

Request syntax example with placeholder values


dynamodb.create_table({
  attribute_definitions: [ # required
    {
      attribute_name: "KeySchemaAttributeName", # required
      attribute_type: "S", # required, accepts S, N, B
    },
  ],
  table_name: "TableName", # required
  key_schema: [ # required
    {
      attribute_name: "KeySchemaAttributeName", # required
      key_type: "HASH", # required, accepts HASH, RANGE
    },
  ],
  local_secondary_indexes: [
    {
      index_name: "IndexName", # required
      key_schema: [ # required
        {
          attribute_name: "KeySchemaAttributeName", # required
          key_type: "HASH", # required, accepts HASH, RANGE
        },
      ],
      projection: { # required
        projection_type: "ALL", # accepts ALL, KEYS_ONLY, INCLUDE
        non_key_attributes: ["NonKeyAttributeName"],
      },
    },
  ],
  global_secondary_indexes: [
    {
      index_name: "IndexName", # required
      key_schema: [ # required
        {
          attribute_name: "KeySchemaAttributeName", # required
          key_type: "HASH", # required, accepts HASH, RANGE
        },
      ],
      projection: { # required
        projection_type: "ALL", # accepts ALL, KEYS_ONLY, INCLUDE
        non_key_attributes: ["NonKeyAttributeName"],
      },
      provisioned_throughput: { # required
        read_capacity_units: 1, # required
        write_capacity_units: 1, # required
      },
    },
  ],
  provisioned_throughput: { # required
    read_capacity_units: 1, # required
    write_capacity_units: 1, # required
  },
  stream_specification: {
    stream_enabled: false,
    stream_view_type: "NEW_IMAGE", # accepts NEW_IMAGE, OLD_IMAGE, NEW_AND_OLD_IMAGES, KEYS_ONLY
  },
})

Basic usage

table = dynamodb.create_table(options)
table.name
#=> "table-name"

Options Hash (options):

  • :attribute_definitions (required, Array<Types::AttributeDefinition>)

    An array of attributes that describe the key schema for the table and indexes.

  • :table_name (required, String)

    The name of the table to create.

  • :key_schema (required, Array<Types::KeySchemaElement>)

    Specifies the attributes that make up the primary key for a table or an index. 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 - The role that the key attribute will assume:

      • HASH - partition key

      • RANGE - sort key

    The partition key of an item is also known as its hash attribute. The term \"hash attribute\" derives from DynamoDB\' usage of an internal hash function to evenly distribute data items across partitions, based on their partition key values.

    The sort key of an item is also known as its range attribute. The term \"range attribute\" derives from the way DynamoDB stores items with the same partition key physically close together, in sorted order by the sort key value.

    For a simple primary key (partition key), you must provide exactly one element with a KeyType of HASH.

    For a composite primary key (partition key and sort key), you must provide 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.

  • :local_secondary_indexes (Array<Types::LocalSecondaryIndex>)

    One or more local secondary indexes (the maximum is five) to be created on the table. Each index is scoped to a given partition key value. There is a 10 GB size limit per partition key value; otherwise, the size of a local secondary index is unconstrained.

    Each local secondary index in the array includes the following:

    • IndexName - The name of the local secondary index. Must be unique only for this table.

    • KeySchema - Specifies the key schema for the local secondary index. The key schema must begin with the same partition key 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 secondary index. The total count of attributes provided in NonKeyAttributes, summed across all of the 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.

  • :global_secondary_indexes (Array<Types::GlobalSecondaryIndex>)

    One or more global secondary indexes (the maximum is five) to be created on the table. Each global secondary index in the array includes the following:

    • IndexName - The name of the global secondary index. Must be unique only for this table.

    • KeySchema - Specifies the key schema for the global secondary index.

    • 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 secondary index. The total count of attributes provided in NonKeyAttributes, summed across all of the 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.

    • ProvisionedThroughput - The provisioned throughput settings for the global secondary index, consisting of read and write capacity units.

  • :provisioned_throughput (required, Types::ProvisionedThroughput)

    Represents the provisioned throughput settings for a specified table or index. The settings can be modified using the UpdateTable operation.

    For current minimum and maximum provisioned throughput values, see Limits in the Amazon DynamoDB Developer Guide.

  • :stream_specification (Types::StreamSpecification)

    The settings for DynamoDB Streams on the table. These settings consist of:

    • StreamEnabled - Indicates whether Streams is to be enabled (true) or disabled (false).

    • StreamViewType - When an item in the table is modified, StreamViewType determines what information is written to the table\'s stream. Valid values for StreamViewType are:

      • KEYS_ONLY - Only the key attributes of the modified item are written to the stream.

      • NEW_IMAGE - The entire item, as it appears after it was modified, is written to the stream.

      • OLD_IMAGE - The entire item, as it appeared before it was modified, is written to the stream.

      • NEW_AND_OLD_IMAGES - Both the new and the old item images of the item are written to the stream.

Returns:

See Also:

#table(name) ⇒ Table

Parameters:

Returns:

See Also:

#tables(options = {}) ⇒ Collection<Table>

Returns a Collection of Table resources. No API requests are made until you call an enumerable method on the collection. Client#list_tables will be called multiple times until every Table has been yielded.

Examples:

Request syntax example with placeholder values


dynamodb.tables({
  exclusive_start_table_name: "TableName",
  limit: 1,
})

Enumerating Table resources.

dynamodb.tables.each do |table|
  # yields each table
end

Enumerating Table resources with a limit.

dynamodb.tables.limit(10).each do |table|
  # yields at most 10 tables
end

Options Hash (options):

  • :exclusive_start_table_name (String)

    The first table name that this operation will evaluate. Use the value that was returned for LastEvaluatedTableName in a previous operation, so that you can obtain the next page of results.

  • :limit (Integer)

    A maximum number of table names to return. If this parameter is not specified, the limit is 100.

Returns:

See Also: