Amazon DynamoDB
API Reference (API Version 2012-08-10)
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Query

A Query operation uses the primary key of a table or a secondary index to directly access items from that table or index.

Use the KeyConditionExpression parameter to provide a specific hash key value. The Query operation will return all of the items from the table or index with that hash key value. You can optionally narrow the scope of the Query operation by specifying a range key value and a comparison operator in KeyConditionExpression. You can use the ScanIndexForward parameter to get results in forward or reverse order, by range key or by index key.

Queries that do not return results consume the minimum number of read capacity units for that type of read operation.

If the total number of items meeting the query criteria exceeds the result set size limit of 1 MB, the query stops and results are returned to the user with the LastEvaluatedKey element to continue the query in a subsequent operation. Unlike a Scan operation, a Query operation never returns both an empty result set and a LastEvaluatedKey value. LastEvaluatedKey is only provided if the results exceed 1 MB, or if you have used the Limit parameter.

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.

Request Syntax

{
    "AttributesToGet": [
        "string"
    ],
    "ConditionalOperator": "string",
    "ConsistentRead": boolean,
    "ExclusiveStartKey": 
        {
            "string" :
                {
                    "B": blob,
                    "BOOL": boolean,
                    "BS": [
                        blob
                    ],
                    "L": [
                        AttributeValue
                    ],
                    "M": 
                        {
                            "string" :
                                AttributeValue
                        },
                    "N": "string",
                    "NS": [
                        "string"
                    ],
                    "NULL": boolean,
                    "S": "string",
                    "SS": [
                        "string"
                    ]
                }
        },
    "ExpressionAttributeNames": 
        {
            "string" :
                "string"
        },
    "ExpressionAttributeValues": 
        {
            "string" :
                {
                    "B": blob,
                    "BOOL": boolean,
                    "BS": [
                        blob
                    ],
                    "L": [
                        AttributeValue
                    ],
                    "M": 
                        {
                            "string" :
                                AttributeValue
                        },
                    "N": "string",
                    "NS": [
                        "string"
                    ],
                    "NULL": boolean,
                    "S": "string",
                    "SS": [
                        "string"
                    ]
                }
        },
    "FilterExpression": "string",
    "IndexName": "string",
    "KeyConditionExpression": "string",
    "KeyConditions": 
        {
            "string" :
                {
                    "AttributeValueList": [
                        {
                            "B": blob,
                            "BOOL": boolean,
                            "BS": [
                                blob
                            ],
                            "L": [
                                AttributeValue
                            ],
                            "M": 
                                {
                                    "string" :
                                        AttributeValue
                                },
                            "N": "string",
                            "NS": [
                                "string"
                            ],
                            "NULL": boolean,
                            "S": "string",
                            "SS": [
                                "string"
                            ]
                        }
                    ],
                    "ComparisonOperator": "string"
                }
        },
    "Limit": number,
    "ProjectionExpression": "string",
    "QueryFilter": 
        {
            "string" :
                {
                    "AttributeValueList": [
                        {
                            "B": blob,
                            "BOOL": boolean,
                            "BS": [
                                blob
                            ],
                            "L": [
                                AttributeValue
                            ],
                            "M": 
                                {
                                    "string" :
                                        AttributeValue
                                },
                            "N": "string",
                            "NS": [
                                "string"
                            ],
                            "NULL": boolean,
                            "S": "string",
                            "SS": [
                                "string"
                            ]
                        }
                    ],
                    "ComparisonOperator": "string"
                }
        },
    "ReturnConsumedCapacity": "string",
    "ScanIndexForward": boolean,
    "Select": "string",
    "TableName": "string"
}

Request Parameters

The request requires the following data in JSON format.

Note

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

TableName

The name of the table containing the requested items.

Type: String

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

Pattern: [a-zA-Z0-9_.-]+

Required: Yes

AttributesToGet

Important

This is a legacy parameter, for backward compatibility. New applications should use ProjectionExpression instead. Do not combine legacy parameters and expression parameters in a single API call; otherwise, DynamoDB will return a ValidationException exception. This parameter allows you to retrieve attributes of type List or Map; however, it cannot retrieve individual elements within a List or a Map.

The names of one or more attributes to retrieve. If no attribute names are provided, then all attributes will be returned. If any of the requested attributes are not found, they will not appear in the result.

Note that AttributesToGet has no effect on provisioned throughput consumption. DynamoDB determines capacity units consumed based on item size, not on the amount of data that is returned to an application.

You cannot use both AttributesToGet and Select together in a Query request, unless the value for Select is SPECIFIC_ATTRIBUTES. (This usage is equivalent to specifying AttributesToGet without any value for Select.)

If you query a local secondary index and request only attributes that are projected into that index, the operation will read only the index and not the table. If any of the requested attributes are not projected into the local secondary index, DynamoDB will fetch each of these attributes from the parent table. This extra fetching incurs additional throughput cost and latency.

If you query a global secondary index, you can only request attributes that are projected into the index. Global secondary index queries cannot fetch attributes from the parent table.

Type: array of Strings

Length constraints: Minimum of 1 item(s) in the list.

Required: No

ConditionalOperator

Important

This is a legacy parameter, for backward compatibility. New applications should use FilterExpression instead. Do not combine legacy parameters and expression parameters in a single API call; otherwise, DynamoDB will return a ValidationException exception.

A logical operator to apply to the conditions in a QueryFilter map:

  • AND - If all of the conditions evaluate to true, then the entire map evaluates to true.

  • OR - If at least one of the conditions evaluate to true, then the entire map evaluates to true.

If you omit ConditionalOperator, then AND is the default.

The operation will succeed only if the entire map evaluates to true.

Note

This parameter does not support attributes of type List or Map.

Type: String

Valid Values: AND | OR

Required: No

ConsistentRead

Determines the read consistency model: If set to true, then the operation uses strongly consistent reads; otherwise, the operation uses eventually consistent reads.

Strongly consistent reads are not supported on global secondary indexes. If you query a global secondary index with ConsistentRead set to true, you will receive a ValidationException.

Type: Boolean

Required: No

ExclusiveStartKey

The primary key of the first item that this operation will evaluate. Use the value that was returned for LastEvaluatedKey in the previous operation.

The data type for ExclusiveStartKey must be String, Number or Binary. No set data types are allowed.

Type: String to AttributeValue object map

Required: No

ExpressionAttributeNames

One or more substitution tokens for attribute names in an expression. 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

Note

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.

Type: String to String map

Required: No

ExpressionAttributeValues

One or more values that can be substituted in an expression.

Use the : (colon) character in an expression to dereference an attribute value. For example, suppose that you wanted to check whether the value of the ProductStatus attribute was one of the following:

Available | Backordered | Discontinued

You would first need to specify ExpressionAttributeValues as follows:

{ ":avail":{"S":"Available"}, ":back":{"S":"Backordered"}, ":disc":{"S":"Discontinued"} }

You could then use these values in an expression, such as this:

ProductStatus IN (:avail, :back, :disc)

For more information on expression attribute values, see Specifying Conditions in the Amazon DynamoDB Developer Guide.

Type: String to AttributeValue object map

Required: No

FilterExpression

A string that contains conditions that DynamoDB applies after the Query operation, but before the data is returned to you. Items that do not satisfy the FilterExpression criteria are not returned.

Note

A FilterExpression is applied after the items have already been read; the process of filtering does not consume any additional read capacity units.

For more information, see Filter Expressions in the Amazon DynamoDB Developer Guide.

Note

FilterExpression replaces the legacy QueryFilter and ConditionalOperator parameters.

Type: String

Required: No

IndexName

The name of an index to query. This index can be any local secondary index or global secondary index on the table. Note that if you use the IndexName parameter, you must also provide TableName.

Type: String

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

Pattern: [a-zA-Z0-9_.-]+

Required: No

KeyConditionExpression

The condition that specifies the key value(s) for items to be retrieved by the Query action.

The condition must perform an equality test on a single hash key value. The condition can also perform one of several comparison tests on a single range key value. Query can use KeyConditionExpression to retrieve one item with a given hash and range key value, or several items that have the same hash key value but different range key values.

The hash key equality test is required, and must be specified in the following format:

hashAttributeName = :hashval

If you also want to provide a range key condition, it must be combined using AND with the hash key condition. Following is an example, using the = comparison operator for the range key:

hashAttributeName = :hashval AND rangeAttributeName = :rangeval

Valid comparisons for the range key condition are as follows:

  • rangeAttributeName = :rangeval - true if the range key is equal to :rangeval.

  • rangeAttributeName < :rangeval - true if the range key is less than :rangeval.

  • rangeAttributeName <= :rangeval - true if the range key is less than or equal to :rangeval.

  • rangeAttributeName > :rangeval - true if the range key is greater than :rangeval.

  • rangeAttributeName >= :rangeval - true if the range key is greater than or equal to :rangeval.

  • rangeAttributeName BETWEEN :rangeval1 AND :rangeval2 - true if the range key is greater than or equal to :rangeval1, and less than or equal to :rangeval2.

  • begins_with ( rangeAttributeName, :rangeval ) - true if the range key begins with a particular operand. (You cannot use this function with a range key that is of type Number.) Note that the function name begins_with is case-sensitive.

Use the ExpressionAttributeValues parameter to replace tokens such as :hashval and :rangeval with actual values at runtime.

You can optionally use the ExpressionAttributeNames parameter to replace the names of the hash and range attributes with placeholder tokens. This option might be necessary if an attribute name conflicts with a DynamoDB reserved word. For example, the following KeyConditionExpression parameter causes an error because Size is a reserved word:

  • Size = :myval

To work around this, define a placeholder (such a #S) to represent the attribute name Size. KeyConditionExpression then is as follows:

  • #S = :myval

For a list of reserved words, see Reserved Words in the Amazon DynamoDB Developer Guide.

For more information on ExpressionAttributeNames and ExpressionAttributeValues, see Using Placeholders for Attribute Names and Values in the Amazon DynamoDB Developer Guide.

Note

KeyConditionExpression replaces the legacy KeyConditions parameter.

Type: String

Required: No

KeyConditions

Important

This is a legacy parameter, for backward compatibility. New applications should use KeyConditionExpression instead. Do not combine legacy parameters and expression parameters in a single API call; otherwise, DynamoDB will return a ValidationException exception.

The selection criteria for the query. For a query on a table, you can have conditions only on the table primary key attributes. You must provide the hash key attribute name and value as an EQ condition. You can optionally provide a second condition, referring to the range key attribute.

Note

If you don't provide a range key condition, all of the items that match the hash key will be retrieved. If a FilterExpression or QueryFilter is present, it will be applied after the items are retrieved.

For a query on an index, you can have conditions only on the index key attributes. You must provide the index hash attribute name and value as an EQ condition. You can optionally provide a second condition, referring to the index key range attribute.

Each KeyConditions element consists of an attribute name to compare, along with the following:

  • AttributeValueList - One or more values to evaluate against the supplied attribute. The number of values in the list depends on the ComparisonOperator being used.

    For type Number, value comparisons are numeric.

    String value comparisons for greater than, equals, or less than are based on ASCII character code values. For example, a is greater than A, and a is greater than B. For a list of code values, see http://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters.

    For Binary, DynamoDB treats each byte of the binary data as unsigned when it compares binary values.

  • ComparisonOperator - A comparator for evaluating attributes, for example, equals, greater than, less than, and so on.

    For KeyConditions, only the following comparison operators are supported:

    EQ | LE | LT | GE | GT | BEGINS_WITH | BETWEEN

    The following are descriptions of these comparison operators.

    • EQ : Equal.

      AttributeValueList can contain only one AttributeValue of type String, Number, or Binary (not a set type). If an item contains an AttributeValue element of a different type than the one specified in the request, the value does not match. For example, {"S":"6"} does not equal {"N":"6"}. Also, {"N":"6"} does not equal {"NS":["6", "2", "1"]}.

    • LE : Less than or equal.

      AttributeValueList can contain only one AttributeValue element of type String, Number, or Binary (not a set type). If an item contains an AttributeValue element of a different type than the one provided in the request, the value does not match. For example, {"S":"6"} does not equal {"N":"6"}. Also, {"N":"6"} does not compare to {"NS":["6", "2", "1"]}.

    • LT : Less than.

      AttributeValueList can contain only one AttributeValue of type String, Number, or Binary (not a set type). If an item contains an AttributeValue element of a different type than the one provided in the request, the value does not match. For example, {"S":"6"} does not equal {"N":"6"}. Also, {"N":"6"} does not compare to {"NS":["6", "2", "1"]}.

    • GE : Greater than or equal.

      AttributeValueList can contain only one AttributeValue element of type String, Number, or Binary (not a set type). If an item contains an AttributeValue element of a different type than the one provided in the request, the value does not match. For example, {"S":"6"} does not equal {"N":"6"}. Also, {"N":"6"} does not compare to {"NS":["6", "2", "1"]}.

    • GT : Greater than.

      AttributeValueList can contain only one AttributeValue element of type String, Number, or Binary (not a set type). If an item contains an AttributeValue element of a different type than the one provided in the request, the value does not match. For example, {"S":"6"} does not equal {"N":"6"}. Also, {"N":"6"} does not compare to {"NS":["6", "2", "1"]}.

    • BEGINS_WITH : Checks for a prefix.

      AttributeValueList can contain only one AttributeValue of type String or Binary (not a Number or a set type). The target attribute of the comparison must be of type String or Binary (not a Number or a set type).

    • BETWEEN : Greater than or equal to the first value, and less than or equal to the second value.

      AttributeValueList must contain two AttributeValue elements of the same type, either String, Number, or Binary (not a set type). A target attribute matches if the target value is greater than, or equal to, the first element and less than, or equal to, the second element. If an item contains an AttributeValue element of a different type than the one provided in the request, the value does not match. For example, {"S":"6"} does not compare to {"N":"6"}. Also, {"N":"6"} does not compare to {"NS":["6", "2", "1"]}

For usage examples of AttributeValueList and ComparisonOperator, see Legacy Conditional Parameters in the Amazon DynamoDB Developer Guide.

Type: String to Condition object map

Required: No

Limit

The maximum number of items to evaluate (not necessarily the number of matching items). If DynamoDB processes the number of items up to the limit while processing the results, it stops the operation and returns the matching values up to that point, and a key in LastEvaluatedKey to apply in a subsequent operation, so that you can pick up where you left off. Also, if the processed data set size exceeds 1 MB before DynamoDB reaches this limit, it stops the operation and returns the matching values up to the limit, and a key in LastEvaluatedKey to apply in a subsequent operation to continue the operation. For more information, see Query and Scan in the Amazon DynamoDB Developer Guide.

Type: Number

Valid range: Minimum value of 1.

Required: No

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.

Note

ProjectionExpression replaces the legacy AttributesToGet parameter.

Type: String

Required: No

QueryFilter

Important

This is a legacy parameter, for backward compatibility. New applications should use FilterExpression instead. Do not combine legacy parameters and expression parameters in a single API call; otherwise, DynamoDB will return a ValidationException exception.

A condition that evaluates the query results after the items are read and returns only the desired values.

This parameter does not support attributes of type List or Map.

Note

A QueryFilter is applied after the items have already been read; the process of filtering does not consume any additional read capacity units.

If you provide more than one condition in the QueryFilter map, then by default all of the conditions must evaluate to true. In other words, the conditions are ANDed together. (You can use the ConditionalOperator parameter to OR the conditions instead. If you do this, then at least one of the conditions must evaluate to true, rather than all of them.)

Note that QueryFilter does not allow key attributes. You cannot define a filter condition on a hash key or range key.

Each QueryFilter element consists of an attribute name to compare, along with the following:

  • AttributeValueList - One or more values to evaluate against the supplied attribute. The number of values in the list depends on the operator specified in ComparisonOperator.

    For type Number, value comparisons are numeric.

    String value comparisons for greater than, equals, or less than are based on ASCII character code values. For example, a is greater than A, and a is greater than B. For a list of code values, see http://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters.

    For type Binary, DynamoDB treats each byte of the binary data as unsigned when it compares binary values.

    For information on specifying data types in JSON, see JSON Data Format in the Amazon DynamoDB Developer Guide.

  • ComparisonOperator - A comparator for evaluating attributes. For example, equals, greater than, less than, etc.

    The following comparison operators are available:

    EQ | NE | LE | LT | GE | GT | NOT_NULL | NULL | CONTAINS | NOT_CONTAINS | BEGINS_WITH | IN | BETWEEN

    For complete descriptions of all comparison operators, see the Condition data type.

Type: String to Condition object map

Required: No

ReturnConsumedCapacity

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.

Type: String

Valid Values: INDEXES | TOTAL | NONE

Required: No

ScanIndexForward

Specifies the order for index traversal: If true (default), the traversal is performed in ascending order; if false, the traversal is performed in descending order.

Items with the same hash key are stored in sorted order by range key. If the range key data type is Number, the results are stored in numeric order. For type String, the results are stored in order of ASCII character code values. For type Binary, DynamoDB treats each byte of the binary data as unsigned.

If ScanIndexForward is true, DynamoDB returns the results in the order in which they are stored (by range key). This is the default behavior. If ScanIndexForward is false, DynamoDB reads the results in reverse order by range key, and then returns the results to the client.

Type: Boolean

Required: No

Select

The attributes to be returned in the result. You can retrieve all item attributes, specific item attributes, the count of matching items, or in the case of an index, some or all of the attributes projected into the index.

  • ALL_ATTRIBUTES - Returns all of the item attributes from the specified table or index. If you query a local secondary index, then for each matching item in the index DynamoDB will fetch the entire item from the parent table. If the index is configured to project all item attributes, then all of the data can be obtained from the local secondary index, and no fetching is required.

  • ALL_PROJECTED_ATTRIBUTES - Allowed only when querying an index. Retrieves all attributes that have been projected into the index. If the index is configured to project all attributes, this return value is equivalent to specifying ALL_ATTRIBUTES.

  • COUNT - Returns the number of matching items, rather than the matching items themselves.

  • SPECIFIC_ATTRIBUTES - Returns only the attributes listed in AttributesToGet. This return value is equivalent to specifying AttributesToGet without specifying any value for Select.

    If you query a local secondary index and request only attributes that are projected into that index, the operation will read only the index and not the table. If any of the requested attributes are not projected into the local secondary index, DynamoDB will fetch each of these attributes from the parent table. This extra fetching incurs additional throughput cost and latency.

    If you query a global secondary index, you can only request attributes that are projected into the index. Global secondary index queries cannot fetch attributes from the parent table.

If neither Select nor AttributesToGet are specified, DynamoDB defaults to ALL_ATTRIBUTES when accessing a table, and ALL_PROJECTED_ATTRIBUTES when accessing an index. You cannot use both Select and AttributesToGet together in a single request, unless the value for Select is SPECIFIC_ATTRIBUTES. (This usage is equivalent to specifying AttributesToGet without any value for Select.)

Note

If you use the ProjectionExpression parameter, then the value for Select can only be SPECIFIC_ATTRIBUTES. Any other value for Select will return an error.

Type: String

Valid Values: ALL_ATTRIBUTES | ALL_PROJECTED_ATTRIBUTES | SPECIFIC_ATTRIBUTES | COUNT

Required: No

Response Syntax

{
    "ConsumedCapacity": {
        "CapacityUnits": number,
        "GlobalSecondaryIndexes": 
            {
                "string" :
                    {
                        "CapacityUnits": number
                    }
            },
        "LocalSecondaryIndexes": 
            {
                "string" :
                    {
                        "CapacityUnits": number
                    }
            },
        "Table": {
            "CapacityUnits": number
        },
        "TableName": "string"
    },
    "Count": number,
    "Items": [
        
            {
                "string" :
                    {
                        "B": blob,
                        "BOOL": boolean,
                        "BS": [
                            blob
                        ],
                        "L": [
                            AttributeValue
                        ],
                        "M": 
                            {
                                "string" :
                                    AttributeValue
                            },
                        "N": "string",
                        "NS": [
                            "string"
                        ],
                        "NULL": boolean,
                        "S": "string",
                        "SS": [
                            "string"
                        ]
                    }
            }
    ],
    "LastEvaluatedKey": 
        {
            "string" :
                {
                    "B": blob,
                    "BOOL": boolean,
                    "BS": [
                        blob
                    ],
                    "L": [
                        AttributeValue
                    ],
                    "M": 
                        {
                            "string" :
                                AttributeValue
                        },
                    "N": "string",
                    "NS": [
                        "string"
                    ],
                    "NULL": boolean,
                    "S": "string",
                    "SS": [
                        "string"
                    ]
                }
        },
    "ScannedCount": number
}

Response Elements

If the action is successful, the service sends back an HTTP 200 response.

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

ConsumedCapacity

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 the request asked for it. For more information, see Provisioned Throughput in the Amazon DynamoDB Developer Guide.

Type: ConsumedCapacity object

Count

The number of items in the response.

If you used a QueryFilter in the request, then Count is the number of items returned after the filter was applied, and ScannedCount is the number of matching items before> the filter was applied.

If you did not use a filter in the request, then Count and ScannedCount are the same.

Type: Number

Items

An array of item attributes that match the query criteria. Each element in this array consists of an attribute name and the value for that attribute.

Type: array of s

LastEvaluatedKey

The primary key of the item where the operation stopped, inclusive of the previous result set. Use this value to start a new operation, excluding this value in the new request.

If LastEvaluatedKey is empty, then the "last page" of results has been processed and there is no more data to be retrieved.

If LastEvaluatedKey is not empty, it does not necessarily mean that there is more data in the result set. The only way to know when you have reached the end of the result set is when LastEvaluatedKey is empty.

Type: String to AttributeValue object map

ScannedCount

The number of items evaluated, before any QueryFilter is applied. A high ScannedCount value with few, or no, Count results indicates an inefficient Query operation. For more information, see Count and ScannedCount in the Amazon DynamoDB Developer Guide.

If you did not use a filter in the request, then ScannedCount is the same as Count.

Type: Number

Errors

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

InternalServerError

An error occurred on the server side.

HTTP Status Code: 500

ProvisionedThroughputExceededException

Your request rate is too high. The AWS SDKs for DynamoDB automatically retry requests that receive this exception. Your request is eventually successful, unless your retry queue is too large to finish. Reduce the frequency of requests and use exponential backoff. For more information, go to 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 might not be specified correctly, or its status might not be ACTIVE.

HTTP Status Code: 400

Examples

Retrieve a Range of Items

The following example queries the Reply table for replies in a forum that were posted by particular users. There is a local secondary index on the Reply table, PostedBy-Index, to facilitate fast lookups on the these attributes. The ProjectionExpression parameter determines which attributes are returned.

Sample Request

POST / HTTP/1.1
Host: dynamodb.<region>.<domain>;
X-Amz-Date: <Date>
Authorization: AWS4-HMAC-SHA256 Credential=<Credential>, SignedHeaders=<Headers>, 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.Query 

{
    "TableName": "Reply",
    "IndexName": "PostedBy-Index",
    "Limit": 3,
    "ConsistentRead": true,
    "ProjectionExpression": "Id, PostedBy, ReplyDateTime",
    "KeyConditionExpression": "Id = :v1 AND PostedBy BETWEEN :v2a AND :v2b",
    "ExpressionAttributeValues": {
        ":v1": {"S": "Amazon DynamoDB#DynamoDB Thread 1"},
        ":v2a": {"S": "User A"},
        ":v2b": {"S": "User C"}
    },
    "ReturnConsumedCapacity": "TOTAL"
}
        

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>
 {
    "ConsumedCapacity": {
        "CapacityUnits": 1,
        "TableName": "Reply"
    },
    "Count": 2,
    "Items": [
        {
            "ReplyDateTime": {"S": "2015-02-18T20:27:36.165Z"},
            "PostedBy": {"S": "User A"},
            "Id": {"S": "Amazon DynamoDB#DynamoDB Thread 1"}
        },
        {
            "ReplyDateTime": {"S": "2015-02-25T20:27:36.165Z"},
            "PostedBy": {"S": "User B"},
            "Id": {"S": "Amazon DynamoDB#DynamoDB Thread 1"}
        }
    ],
    "ScannedCount": 2
}
        

Count Items

The following example returns the number of items in the Thread table for a particular forum.

Sample Request

POST / HTTP/1.1
Host: dynamodb.<region>.<domain>;
X-Amz-Date: <Date>
Authorization: AWS4-HMAC-SHA256 Credential=<Credential>, SignedHeaders=<Headers>, 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.Query 

{
    "TableName": "Thread",
    "ConsistentRead": true,
    "KeyConditionExpression": "ForumName = :val",
    "ExpressionAttributeValues": {":val": {"S": "Amazon DynamoDB"}}
}
        

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>
 {
          "Count":2,
          "ScannedCount":2
}