Class ScanCommandProtected

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.

import { DynamoDBClient, ScanCommand } from "@aws-sdk/client-dynamodb"; // ES Modules import
// const { DynamoDBClient, ScanCommand } = require("@aws-sdk/client-dynamodb"); // CommonJS import
const client = new DynamoDBClient(config);
const input = { // ScanInput
  TableName: "STRING_VALUE", // required
  IndexName: "STRING_VALUE",
  AttributesToGet: [ // AttributeNameList
    "STRING_VALUE",
  ],
  Limit: Number("int"),
  Select: "ALL_ATTRIBUTES" || "ALL_PROJECTED_ATTRIBUTES" || "SPECIFIC_ATTRIBUTES" || "COUNT",
  ScanFilter: { // FilterConditionMap
    "<keys>": { // Condition
      AttributeValueList: [ // AttributeValueList
        { // AttributeValue Union: only one key present
          S: "STRING_VALUE",
          N: "STRING_VALUE",
          B: "BLOB_VALUE",
          SS: [ // StringSetAttributeValue
            "STRING_VALUE",
          ],
          NS: [ // NumberSetAttributeValue
            "STRING_VALUE",
          ],
          BS: [ // BinarySetAttributeValue
            "BLOB_VALUE",
          ],
          M: { // MapAttributeValue
            "<keys>": {//  Union: only one key present
              S: "STRING_VALUE",
              N: "STRING_VALUE",
              B: "BLOB_VALUE",
              SS: [
                "STRING_VALUE",
              ],
              NS: [
                "STRING_VALUE",
              ],
              BS: [
                "BLOB_VALUE",
              ],
              M: {
                "<keys>": "<AttributeValue>",
              },
              L: [ // ListAttributeValue
                "<AttributeValue>",
              ],
              NULL: true || false,
              BOOL: true || false,
            },
          },
          L: [
            "<AttributeValue>",
          ],
          NULL: true || false,
          BOOL: true || false,
        },
      ],
      ComparisonOperator: "EQ" || "NE" || "IN" || "LE" || "LT" || "GE" || "GT" || "BETWEEN" || "NOT_NULL" || "NULL" || "CONTAINS" || "NOT_CONTAINS" || "BEGINS_WITH", // required
    },
  },
  ConditionalOperator: "AND" || "OR",
  ExclusiveStartKey: { // Key
    "<keys>": "<AttributeValue>",
  },
  ReturnConsumedCapacity: "INDEXES" || "TOTAL" || "NONE",
  TotalSegments: Number("int"),
  Segment: Number("int"),
  ProjectionExpression: "STRING_VALUE",
  FilterExpression: "STRING_VALUE",
  ExpressionAttributeNames: { // ExpressionAttributeNameMap
    "<keys>": "STRING_VALUE",
  },
  ExpressionAttributeValues: { // ExpressionAttributeValueMap
    "<keys>": "<AttributeValue>",
  },
  ConsistentRead: true || false,
};
const command = new ScanCommand(input);
const response = await client.send(command);

Param

ScanCommandInput

Returns

ScanCommandOutput

See

• ScanCommandInput for command's input shape.
• ScanCommandOutput for command's response shape.
• config for DynamoDBClient's 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

// 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.
const input = {
  "ExpressionAttributeNames": {
    "#AT": "AlbumTitle",
    "#ST": "SongTitle"
  },
  "ExpressionAttributeValues": {
    ":a": {
      "S": "No One You Know"
    }
  },
  "FilterExpression": "Artist = :a",
  "ProjectionExpression": "#ST, #AT",
  "TableName": "Music"
};
const command = new ScanCommand(input);
const response = await client.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