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.
Example
Use a bare-bones client and the command you need to make an API call.
Your request rate is too high. The Amazon Web Services 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.
The operation tried to access a nonexistent table or index. The resource might not
be specified correctly, or its status might not be ACTIVE.
Example
To scan a table
// This example scans the entire Music table, and then narrows the results to songs by the artist "No One You Know". For each item, only the album title and song title are returned. constinput = { "ExpressionAttributeNames": { "#AT":"AlbumTitle", "#ST":"SongTitle" }, "ExpressionAttributeValues": { ":a": { "S":"No One You Know" } }, "FilterExpression":"Artist = :a", "ProjectionExpression":"#ST, #AT", "TableName":"Music" }; constcommand = newScanCommand(input); constresponse = awaitclient.send(command); /* response == { "ConsumedCapacity": {}, "Count": 2, "Items": [ { "AlbumTitle": { "S": "Somewhat Famous" }, "SongTitle": { "S": "Call Me Today" } }, { "AlbumTitle": { "S": "Blue Sky Blues" }, "SongTitle": { "S": "Scared of My Shadow" } } ], "ScannedCount": 3 } */ // example id: to-scan-a-table-1475883652470
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 aFilterExpression
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 theLimit
parameter) or a maximum of 1 MB of data and then apply any filtering to the results usingFilterExpression
. IfLastEvaluatedKey
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 parallelScan
operation by providing theSegment
andTotalSegments
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 theScan
begins, you can set theConsistentRead
parameter totrue
.Example
Use a bare-bones client and the command you need to make an API call.
Param
ScanCommandInput
Returns
ScanCommandOutput
See
input
shape.response
shape.config
shape.Throws
InternalServerError (server fault)
An error occurred on the server side.
Throws
InvalidEndpointException (client fault)
Throws
ProvisionedThroughputExceededException (client fault)
Your request rate is too high. The Amazon Web Services 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.
Throws
RequestLimitExceeded (client fault)
Throughput exceeds the current throughput quota for your account. Please contact Amazon Web Services Support to request a quota increase.
Throws
ResourceNotFoundException (client fault)
The operation tried to access a nonexistent table or index. The resource might not be specified correctly, or its status might not be
ACTIVE
.Example
To scan a table