Amazon DynamoDB
API Reference (API Version 2012-08-10)
« PreviousNext »
View the PDF for this guide.Go to the AWS Discussion Forum for this product.Did this page help you?  Yes | No |  Tell us about it...

DeleteItem

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, DynamoDB performs the delete. Otherwise, the item is not deleted.

Request Syntax

{
    "Expected": 
        {
            "string" :
                {
                    "Exists": "boolean",
                    "Value": {
                        "B": "blob",
                        "BS": [
                            "blob"
                        ],
                        "N": "string",
                        "NS": [
                            "string"
                        ],
                        "S": "string",
                        "SS": [
                            "string"
                        ]
                    }
                }
        },
    "Key": 
        {
            "string" :
                {
                    "B": "blob",
                    "BS": [
                        "blob"
                    ],
                    "N": "string",
                    "NS": [
                        "string"
                    ],
                    "S": "string",
                    "SS": [
                        "string"
                    ]
                }
        },
    "ReturnConsumedCapacity": "string",
    "ReturnItemCollectionMetrics": "string",
    "ReturnValues": "string",
    "TableName": "string"
}
			

Request Parameters

The request accepts the following data in JSON format.

Note

In the following list, the required parameters are described first.

Key

A map of attribute names to AttributeValue objects, representing the primary key of the item to delete.

For the primary key, you must provide all of the attributes. For example, with a hash type primary key, you only need to specify the hash attribute. For a hash-and-range type primary key, you must specify both the hash attribute and the range attribute.

Type: String to AttributeValue object map

Required: Yes

TableName

The name of the table from which to delete the item.

Type: String

Length constraints: Minimum length of 3. Maximum length of 255.

Required: Yes

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 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 DynamoDB to check, along with the following:

  • Value - A value for DynamoDB to compare with an attribute. When performing the comparison, strongly consistent reads are used.

  • Exists - Causes DynamoDB to evaluate the value before attempting a conditional operation:

    • If Exists is true, 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, 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, DynamoDB assumes the attribute exists: You don't have to set Exists to true, because it is implied.

    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: String to ExpectedAttributeValue object map

Required: No

ReturnConsumedCapacity

If set to TOTAL, the response includes ConsumedCapacity data for tables and indexes. If set to INDEXES, the response includes ConsumedCapacity for indexes. If set to NONE (the default), ConsumedCapacity is not included in the response.

Type: String

Valid Values: INDEXES | TOTAL | NONE

Required: No

ReturnItemCollectionMetrics

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.

Type: String

Valid Values: SIZE | NONE

Required: No

ReturnValues

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: String

Valid Values: NONE | ALL_OLD | UPDATED_OLD | ALL_NEW | UPDATED_NEW

Required: No

Response Syntax

{
    "Attributes": 
        {
            "string" :
                {
                    "B": "blob",
                    "BS": [
                        "blob"
                    ],
                    "N": "string",
                    "NS": [
                        "string"
                    ],
                    "S": "string",
                    "SS": [
                        "string"
                    ]
                }
        },
    "ConsumedCapacity": {
        "CapacityUnits": "number",
        "GlobalSecondaryIndexes": 
            {
                "string" :
                    {
                        "CapacityUnits": "number"
                    }
            },
        "LocalSecondaryIndexes": 
            {
                "string" :
                    {
                        "CapacityUnits": "number"
                    }
            },
        "Table": {
            "CapacityUnits": "number"
        },
        "TableName": "string"
    },
    "ItemCollectionMetrics": {
        "ItemCollectionKey": 
            {
                "string" :
                    {
                        "B": "blob",
                        "BS": [
                            "blob"
                        ],
                        "N": "string",
                        "NS": [
                            "string"
                        ],
                        "S": "string",
                        "SS": [
                            "string"
                        ]
                    }
            },
        "SizeEstimateRangeGB": [
            "number"
        ]
    }
}
			

Response Elements

The following data is returned in JSON format by the service.

Attributes

A map of attribute names to AttributeValue objects, representing the item as it appeared before the DeleteItem operation. This map appears in the response only if ReturnValues was specified as ALL_OLD in the request.

Type: String to AttributeValue object map

ConsumedCapacity

Represents the capacity units consumed by an operation. The data returned includes the total provisioned throughput consumed, along with statistics for the table and any indexes involved in the operation. ConsumedCapacity is only returned if it was asked for in the request. For more information, see Provisioned Throughput in the Amazon DynamoDB Developer Guide.

Type: ConsumedCapacity object

ItemCollectionMetrics

Information about item collections, if any, that were affected by the operation. ItemCollectionMetrics is only returned if it was asked for in the request. If the table does not have any local secondary indexes, this information is not returned in the response.

Each ItemCollectionMetrics element consists of:

  • ItemCollectionKey - The hash key value of the item collection. This is the same as the hash key of the item.

  • SizeEstimateRange - An estimate of item collection size, measured in gigabytes. This is a two-element array containing a lower bound and an upper bound for the estimate. The estimate includes the size of all the items in the table, plus the size of all attributes projected into all of the local secondary indexes on that table. Use this estimate to measure whether a local secondary index is approaching its size limit.

    The estimate is subject to change over time; therefore, do not rely on the precision or accuracy of the estimate.

Type: ItemCollectionMetrics object

Errors

For information about the errors that are common to all actions, see Common Errors.

ConditionalCheckFailedException

A condition specified in the operation could not be evaluated.

HTTP Status Code: 400

InternalServerError

An error occurred on the server side.

HTTP Status Code: 500

ItemCollectionSizeLimitExceededException

An item collection is too large. This exception is only returned for tables that have one or more local secondary indexes.

HTTP Status Code: 400

ProvisionedThroughputExceededException

The request rate is too high, or the request is too large, for the available throughput to accommodate. The AWS SDKs automatically retry requests that receive this exception; therefore, your request will eventually succeed, unless the request is too large or your retry queue is too large to finish. Reduce the frequency of requests by using the strategies listed in Error Retries and Exponential Backoff in the Amazon DynamoDB Developer Guide.

HTTP Status Code: 400

ResourceNotFoundException

The operation tried to access a nonexistent table or index. The resource may not be specified correctly, or its status may not be ACTIVE.

HTTP Status Code: 400

Examples

Delete an Item

This example deletes an item from the Thread table, but only if that item does not have an attribute named Replies. Because ReturnValues is set to ALL_OLD, the response contains the item as it appeared before the delete.

Sample Request

POST / HTTP/1.1
Host: dynamodb.<region>.<domain>;
X-Amz-Date: <Date>
Authorization: AWS4-HMAC-SHA256 Credential=<Credential>, SignedHeaders=content-length;content-type;host;user-agent;x-amz-content-sha256;x-amz-date;x-amz-target, Signature=<Signature>
User-Agent: <UserAgentString>
x-amz-content-sha256: <PayloadHash>
Content-Type: application/x-amz-json-1.0
Content-Length: <PayloadSizeBytes>     
Connection: Keep-Alive
X-Amz-Target: DynamoDB_20120810.DeleteItem 

{
    "TableName": "Thread",
    "Key": {
        "ForumName": {
            "S": "Amazon DynamoDB"
        },
        "Subject": {
            "S": "How do I update multiple items?"
        }
    },
    "Expected": {
        "Replies": {
            "Exists": false
        }
    },
    "ReturnValues": "ALL_OLD"
}
        

Sample Response

HTTP/1.1 200 OK
x-amzn-RequestId: <RequestId> 
x-amz-crc32: <Checksum>
Content-Type: application/x-amz-json-1.0
Content-Length: <PayloadSizeBytes>
Date: <Date>

{
    "Attributes": {
        "LastPostedBy": {
            "S": "fred@example.com"
        },
        "ForumName": {
            "S": "Amazon DynamoDB"
        },
        "LastPostDateTime": {
            "S": "201303201023"
        },
        "Tags": {
            "SS": ["Update","Multiple Items","HelpMe"]
        },
        "Subject": {
            "S": "How do I update multiple items?"
        },
        "Message": {
            "S": "I want to update multiple items in a single API call. What's the best way to do that?"
        }
    }
}