AttributesToGet => ArrayRef[Str]

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.

ConditionalOperator => Str

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.

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

ConsistentRead => Bool

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.

ExclusiveStartKey => Paws::DynamoDB::Key

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

ExpressionAttributeNames => Paws::DynamoDB::ExpressionAttributeNameMap

• 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 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:

•

"{""

You could then use this substitution in an expression, as in this example:

•

""

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.

ExpressionAttributeValues => Paws::DynamoDB::ExpressionAttributeValueMap

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.

FilterExpression => Str

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.

FilterExpression replaces the legacy QueryFilter and ConditionalOperator parameters.

IndexName => Str

KeyConditionExpression => Str

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 " the attribute name Size. KeyConditionExpression then is as follows:"

•

""

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.

KeyConditionExpression replaces the legacy KeyConditions parameter.

KeyConditions => Paws::DynamoDB::KeyConditions

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.

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

  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.

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

Limit => Int

ProjectionExpression => Str

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.

ProjectionExpression replaces the legacy AttributesToGet parameter.

QueryFilter => Paws::DynamoDB::FilterConditionMap

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.

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

  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.

ReturnConsumedCapacity => Str

ScanIndexForward => Bool

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 returned 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 order, by range key. This is the default behavior.

If ScanIndexForward is "false", DynamoDB sorts the results in descending order by range key, and then returns the results to the client.

Select => Str

• "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.)

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.

REQUIRED TableName => Str