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BatchGetItem

Description

The BatchGetItem operation returns the attributes for multiple items from multiple tables using their primary keys. The maximum number of items that can be retrieved for a single operation is 100. Also, the number of items retrieved is constrained by a 1 MB size limit. If the response size limit is exceeded or a partial result is returned because the table’s provisioned throughput is exceeded, or because of an internal processing failure, DynamoDB returns an UnprocessedKeys value so you can retry the operation starting with the next item to get. DynamoDB automatically adjusts the number of items returned per page to enforce this limit. For example, even if you ask to retrieve 100 items, but each individual item is 50 KB in size, the system returns 20 items 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 set.

If no items could be processed because of insufficient provisioned throughput on each of the tables involved in the request, DynamoDB returns a ProvisionedThroughputExceededException error.

Requests

Syntax

// This header is abbreviated. For a sample of a complete header, see DynamoDB low-level API.
POST / HTTP/1.1 
x-amz-target: DynamoDB_20111205.BatchGetItem 
content-type: application/x-amz-json-1.0 

{"RequestItems":
    {"Table1": 
        {"Keys": 
            [{"HashKeyElement": {"S":"KeyValue1"}, "RangeKeyElement":{"N":"KeyValue2"}},
            {"HashKeyElement": {"S":"KeyValue3"}, "RangeKeyElement":{"N":"KeyValue4"}},
            {"HashKeyElement": {"S":"KeyValue5"}, "RangeKeyElement":{"N":"KeyValue6"}}],
        "AttributesToGet":["AttributeName1", "AttributeName2", "AttributeName3"]},
    "Table2": 
        {"Keys": 
            [{"HashKeyElement": {"S":"KeyValue4"}}, 
            {"HashKeyElement": {"S":"KeyValue5"}}],
        "AttributesToGet": ["AttributeName4", "AttributeName5", "AttributeName6"]
        }
    }
}

Responses

Syntax

HTTP/1.1 200 
x-amzn-RequestId: 8966d095-71e9-11e0-a498-71d736f27375
content-type: application/x-amz-json-1.0 
content-length: 855

{"Responses":
    {"Table1":
        {"Items":
        [{"AttributeName1": {"S":"AttributeValue"},
        "AttributeName2": {"N":"AttributeValue"},
        "AttributeName3": {"SS":["AttributeValue", "AttributeValue", "AttributeValue"]}
        },
        {"AttributeName1": {"S": "AttributeValue"},
        "AttributeName2": {"S": "AttributeValue"},
        "AttributeName3": {"NS": ["AttributeValue", "AttributeValue", "AttributeValue"]}
        }],
    "ConsumedCapacityUnits":1},
    "Table2": 
        {"Items":
        [{"AttributeName1": {"S":"AttributeValue"},
        "AttributeName2": {"N":"AttributeValue"},
        "AttributeName3": {"SS":["AttributeValue", "AttributeValue", "AttributeValue"]}
        },
        {"AttributeName1": {"S": "AttributeValue"},
        "AttributeName2": {"S": "AttributeValue"},
        "AttributeName3": {"NS": ["AttributeValue", "AttributeValue","AttributeValue"]}
        }],
    "ConsumedCapacityUnits":1}
    },
    "UnprocessedKeys":
        {"Table3": 
        {"Keys": 
            [{"HashKeyElement": {"S":"KeyValue1"}, "RangeKeyElement":{"N":"KeyValue2"}},
            {"HashKeyElement": {"S":"KeyValue3"}, "RangeKeyElement":{"N":"KeyValue4"}},
            {"HashKeyElement": {"S":"KeyValue5"}, "RangeKeyElement":{"N":"KeyValue6"}}],
        "AttributesToGet":["AttributeName1", "AttributeName2", "AttributeName3"]}
        }
}

Special errors

Examples

The following examples show an HTTP POST request and response using the BatchGetItem operation. For examples using the Amazon SDK, see Working with items and attributes.

Sample request

The following sample requests attributes from two different tables.

// This header is abbreviated. 
// For a sample of a complete header, see DynamoDB low-level API.
POST / HTTP/1.1 
x-amz-target: DynamoDB_20111205.BatchGetItem 
content-type: application/x-amz-json-1.0 
content-length: 409

{"RequestItems":
    {"comp1":
        {"Keys":
            [{"HashKeyElement":{"S":"Casey"},"RangeKeyElement":{"N":"1319509152"}},
            {"HashKeyElement":{"S":"Dave"},"RangeKeyElement":{"N":"1319509155"}},
            {"HashKeyElement":{"S":"Riley"},"RangeKeyElement":{"N":"1319509158"}}],
        "AttributesToGet":["user","status"]},
    "comp2":
        {"Keys":
            [{"HashKeyElement":{"S":"Julie"}},{"HashKeyElement":{"S":"Mingus"}}],
        "AttributesToGet":["user","friends"]}
    }
}

Sample response

The following sample is the response.

HTTP/1.1 200 OK
x-amzn-RequestId: GTPQVRM4VJS792J1UFJTKUBVV4KQNSO5AEMVJF66Q9ASUAAJG
content-type: application/x-amz-json-1.0 
content-length: 373
Date: Fri, 02 Sep 2011 23:07:39 GMT

{"Responses":
    {"comp1":
        {"Items":
            [{"status":{"S":"online"},"user":{"S":"Casey"}},
            {"status":{"S":"working"},"user":{"S":"Riley"}},
            {"status":{"S":"running"},"user":{"S":"Dave"}}],
        "ConsumedCapacityUnits":1.5},
    "comp2":
        {"Items":
            [{"friends":{"SS":["Elisabeth", "Peter"]},"user":{"S":"Mingus"}},
            {"friends":{"SS":["Dave", "Peter"]},"user":{"S":"Julie"}}],
        "ConsumedCapacityUnits":1}
    },
    "UnprocessedKeys":{}
}