class Aws::DynamoDB::Types::ScanInput

Represents the input of a `Scan` operation.

@note When making an API call, you may pass ScanInput

data as a hash:

    {
      table_name: "TableName", # required
      index_name: "IndexName",
      attributes_to_get: ["AttributeName"],
      limit: 1,
      select: "ALL_ATTRIBUTES", # accepts ALL_ATTRIBUTES, ALL_PROJECTED_ATTRIBUTES, SPECIFIC_ATTRIBUTES, COUNT
      scan_filter: {
        "AttributeName" => {
          attribute_value_list: ["value"], # value <Hash,Array,String,Numeric,Boolean,IO,Set,nil>
          comparison_operator: "EQ", # required, accepts EQ, NE, IN, LE, LT, GE, GT, BETWEEN, NOT_NULL, NULL, CONTAINS, NOT_CONTAINS, BEGINS_WITH
        },
      },
      conditional_operator: "AND", # accepts AND, OR
      exclusive_start_key: {
        "AttributeName" => "value", # value <Hash,Array,String,Numeric,Boolean,IO,Set,nil>
      },
      return_consumed_capacity: "INDEXES", # accepts INDEXES, TOTAL, NONE
      total_segments: 1,
      segment: 1,
      projection_expression: "ProjectionExpression",
      filter_expression: "ConditionExpression",
      expression_attribute_names: {
        "ExpressionAttributeNameVariable" => "AttributeName",
      },
      expression_attribute_values: {
        "ExpressionAttributeValueVariable" => "value", # value <Hash,Array,String,Numeric,Boolean,IO,Set,nil>
      },
      consistent_read: false,
    }

@!attribute [rw] table_name

The name of the table containing the requested items; or, if you
provide `IndexName`, the name of the table to which that index
belongs.
@return [String]

@!attribute [rw] index_name

The name of a secondary index to scan. This index can be any local
secondary index or global secondary index. Note that if you use the
`IndexName` parameter, you must also provide `TableName`.
@return [String]

@!attribute [rw] attributes_to_get

This is a legacy parameter. Use `ProjectionExpression` instead. For
more information, see [AttributesToGet][1] in the *Amazon DynamoDB
Developer Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/LegacyConditionalParameters.AttributesToGet.html
@return [Array<String>]

@!attribute [rw] 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 dataset 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 [Working with Queries][1]
in the *Amazon DynamoDB Developer Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/QueryAndScan.html
@return [Integer]

@!attribute [rw] 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 fetches 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 or scan a local secondary index and request only
  attributes that are projected into that index, the operation reads
  only the index and not the table. If any of the requested
  attributes are not projected into the local secondary index,
  DynamoDB fetches each of these attributes from the parent table.
  This extra fetching incurs additional throughput cost and latency.

  If you query or scan 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 markdown="1"> 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.

 </note>
@return [String]

@!attribute [rw] scan_filter

This is a legacy parameter. Use `FilterExpression` instead. For more
information, see [ScanFilter][1] in the *Amazon DynamoDB Developer
Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/LegacyConditionalParameters.ScanFilter.html
@return [Hash<String,Types::Condition>]

@!attribute [rw] conditional_operator

This is a legacy parameter. Use `FilterExpression` instead. For more
information, see [ConditionalOperator][1] in the *Amazon DynamoDB
Developer Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/LegacyConditionalParameters.ConditionalOperator.html
@return [String]

@!attribute [rw] exclusive_start_key

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.

In a parallel scan, a `Scan` request that includes
`ExclusiveStartKey` must specify the same segment whose previous
`Scan` returned the corresponding value of `LastEvaluatedKey`.
@return [Hash<String,Types::AttributeValue>]

@!attribute [rw] return_consumed_capacity

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.
@return [String]

@!attribute [rw] total_segments

For a parallel `Scan` request, `TotalSegments` represents the total
number of segments into which the `Scan` operation will be divided.
The value of `TotalSegments` corresponds to the number of
application workers that will perform the parallel scan. For
example, if you want to use four application threads to scan a table
or an index, specify a `TotalSegments` value of 4.

The value for `TotalSegments` must be greater than or equal to 1,
and less than or equal to 1000000. If you specify a `TotalSegments`
value of 1, the `Scan` operation will be sequential rather than
parallel.

If you specify `TotalSegments`, you must also specify `Segment`.
@return [Integer]

@!attribute [rw] segment

For a parallel `Scan` request, `Segment` identifies an individual
segment to be scanned by an application worker.

Segment IDs are zero-based, so the first segment is always 0. For
example, if you want to use four application threads to scan a table
or an index, then the first thread specifies a `Segment` value of 0,
the second thread specifies 1, and so on.

The value of `LastEvaluatedKey` returned from a parallel `Scan`
request must be used as `ExclusiveStartKey` with the same segment ID
in a subsequent `Scan` operation.

The value for `Segment` must be greater than or equal to 0, and less
than the value provided for `TotalSegments`.

If you provide `Segment`, you must also provide `TotalSegments`.
@return [Integer]

@!attribute [rw] projection_expression

A string that identifies one or more attributes to retrieve from the
specified table or index. 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 [Specifying Item Attributes][1] in the
*Amazon DynamoDB Developer Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.AccessingItemAttributes.html
@return [String]

@!attribute [rw] filter_expression

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

<note markdown="1"> A `FilterExpression` is applied after the items have already been
read; the process of filtering does not consume any additional read
capacity units.

 </note>

For more information, see [Filter Expressions][1] in the *Amazon
DynamoDB Developer Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/QueryAndScan.html#FilteringResults
@return [String]

@!attribute [rw] expression_attribute_names

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][1] 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 markdown="1"> Tokens that begin with the **\:** character are *expression
attribute values*, which are placeholders for the actual value at
runtime.

 </note>

For more information on expression attribute names, see [Specifying
Item Attributes][2] in the *Amazon DynamoDB Developer Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ReservedWords.html
[2]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.AccessingItemAttributes.html
@return [Hash<String,String>]

@!attribute [rw] expression_attribute_values

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 [Condition
Expressions][1] in the *Amazon DynamoDB Developer Guide*.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.SpecifyingConditions.html
@return [Hash<String,Types::AttributeValue>]

@!attribute [rw] consistent_read

A Boolean value that determines the read consistency model during
the scan:

* If `ConsistentRead` is `false`, then the data returned from `Scan`
  might not contain the results from other recently completed write
  operations (`PutItem`, `UpdateItem`, or `DeleteItem`).

* If `ConsistentRead` is `true`, then all of the write operations
  that completed before the `Scan` began are guaranteed to be
  contained in the `Scan` response.

The default setting for `ConsistentRead` is `false`.

The `ConsistentRead` parameter is not supported on global secondary
indexes. If you scan a global secondary index with `ConsistentRead`
set to true, you will receive a `ValidationException`.
@return [Boolean]

@see docs.aws.amazon.com/goto/WebAPI/dynamodb-2012-08-10/ScanInput AWS API Documentation

Constants

SENSITIVE