Get Item (Query)

Operation Name

Get Item (Query)

Function Overview

Get items stored in an Amazon DynamoDB table.

This operation uses Query API. For more details on API specifications, refer to the following page.

Data Model

Table model type.

Properties

For details on use of variables, refer to “Variables”.
Basic settings
Item name Required/Optional Use of variables Description Remarks
Name Required Not available Enter the name to show on the script canvas.  
Required settings
Item name Required/Optional Use of variables Description Remarks
Destination Required Not available Select a global resource.
  • [Add]:
    Add a new global resource.
  • [Edit list]:
    Global resource settings can be edited in “Edit resource list” screen.
  
Table name Required Available Select or enter a table name to be read.  
Index name Required Available Select or enter an index name to be read.  
Attribute list Required - Specify attribute list of the index specified in [Index name].
Added rows will be the target columns to read.

Each target column can be operated with the following buttons.
  • [Add]:
    Add a target column.
  • [Up]:
    Move the selected target column upwards by one row.
  • [Down]:
    Move the selected target column downwards by one row.
  • [Delete]:
    Delete the target column.
  
Attribute list/Hash key Optional Not available Displays whether it is a hash key attribute of the index specified in [Index name] or the table specified in [Table name], or not.  
Attribute list/Range key Optional Not available Displays whether it is a range key attribute of the index specified in [Index name] or the table specified in [Table name], or not.  
Attribute list/Attribute name Required Available Enter an attribute name of the table specified in [Table name] or the index specified in [Index name].
  • The specified attribute name is displayed in Mapper schema.
Attribute list/Type Required Not available Select the type of [Attribute name].
  • It is displayed in “<DynamoDB data type> (<Internal data type>)” format.
    • DynamoDB data type:
      Data type supported by Amazon DynamoDB.
    • Internal data type:
      Data type used internally within DataSpider.
      For more details, refer to “Internal Data Types”.
Hash key value Required Available Enter the attribute value of the hash key to be specified as query.  
Property actions
Item name Description Remarks
Update table name list Get table names in the specified destination and set them in [Table name].  
Update index name list Get indexes in the specified table and set them in [Index name].  
Update attribute list Update attribute list of the index specified in [Index name].
  • Enabled when [Index name] is specified.
  • Attribute names and data types are extracted from the items got by executing a scan for the table specified in [Table name] or the index specified in [Index name].
  • When there is an attribute of unsupported DynamoDB data type in the items got by scanning, that is not added to the attribute list.
    • For more details on the supported types, refer to “Amazon DynamoDB Adapter Limitations”.
  • When there is no item in the table specified in [Table name], only the primary key attribute will be set.
    Irrespective of the actual attribute type, sets [String (String)] to the data type.
Range key settings
Item name Required/Optional Use of variables Description Remarks
Range key condition Required Not available Specify the condition of the range key attribute to be specified as query.
  • [EQUAL TO]: (default)
    Extract items with the range key equal to the value specified in [Range key value].
  • [LESS THAN]:
    Extract items with the range key less than the value specified in [Range key value].
  • [LESS THAN OR EQUAL TO]:
    Extract items with the range key less than or equal to the value specified in [Range key value].
  • [GREATER THAN]:
    Extract items with the range key greater than the value specified in [Range key value].
  • [GREATER THAN OR EQUAL TO]:
    Extract items with the range key greater than or equal to the value specified in [Range key value].
  • [BEGINS WITH]:
    Extract items with the range key of String or Binary type that begins with the value specified in [Range key value].
  • [BETWEEN]:
    Extract items with the range key between [Range key start value] and [Range key end value].
  
Range key value Optional Available Specify the attribute value of the range key to be specified as query.  
Range key start value Optional Available Specify the starting value of the range key attribute to be specified as query.
  • Displayed when [BETWEEN] is selected in [Range key condition].
Range key end value Optional Available Specify the ending value of the range key attribute to be specified as query.
  • Displayed when [BETWEEN] is selected in [Range key condition].
Read settings
Item name Required/Optional Use of variables Description Remarks
Strongly consistent read Required Not available Select whether or not to perform strongly consistent read.  
Skip rows where actual type and attribute list type are different Required Not available Select whether or not to skip an item if the attribute type specified in [Attribute list/Type] differs from the actual type, instead of considering it as an error.
  • The details of skipped items will be output in the script execution log.
Data processing method
Item name Required/Optional Use of variables Description Remarks
Data processing method Required Not available Select data processing method.
  • [Apply script settings]: (default)
    Apply the mass data processing settings of the script property to the adapter.
  • [Do not perform mass data processing]:
    Mass data processing will not be performed.
  • [Perform mass data processing]:
    Mass data processing will be performed.
  
Comment
Item name Required/Optional Use of variables Description Remarks
Comment Optional Not available You can write a short description of this adapter.
The description will be reflected in the specifications.		  

Schema

Input schema

None.

Output schema

The number of columns differs depending on the [Attribute list] settings.
For more details, refer to “Schema of table model type”.

Loading schema in Mapper

Schema is loaded automatically.
For more details, refer to “Edit Schema”.

Mass Data Processing

Mass Data Processing is supported.

PSP Usage

PSP is supported.
For more details, refer to “Parallel Stream Processing”.

Available Component Variables

Component variable name Description Remarks
count The number of got items is stored.
  • Default value is null.
skip_count When the type specified in the attribute list differs from the actual type, the number of items skipped is stored.
  • Default value is null.
message_category When an error occurs, the corresponding message code's category is stored.
  • Default value is null.
message_code When an error occurs, the corresponding message code is stored.
  • Default value is null.
message_level When an error occurs, the corresponding message code's severity is stored.
  • Default value is null.
error_type When an error occurs, the error type is stored.
  • Default value is null.
  • The error type will be in the following format.
    Example: “java.io.FileNotFoundException”
  • The contents that will be stored may vary depending on DataSpider Servista versions.
error_message When an error occurs, the error message is stored.
  • Default value is null.
  • The contents that will be stored may vary depending on DataSpider Servista versions.
error_trace When an error occurs, the error's trace information is stored.
  • Default value is null.
  • The contents that will be stored may vary depending on DataSpider Servista versions and client applications.

Specification Limits

For details on specification limits common to the operations, refer to “Amazon DynamoDB Adapter Limitations”.

Major Exceptions

Exception name Cause Solution
ResourceNotFoundException
Resource definition is not found. Name: []		 [Destination] is not specified. Specify [Destination].
ResourceNotFoundException
Resource definition is not found. Name: [<global resource name>]		 The resource definition specified in [Destination] is not found. Check the global resource specified in [Destination].
InvalidPropertyConfigurationException
<property name> is not specified.		 [<property name>] is not specified. Specify [<property name>].
UnexpectedDynamoDBDataTypeException
Data type is different.		 The type of attribute specified in [Attribute list/Type] differs from the actual type. You can avoid the exception by setting the types of the attributes same in the table, or insert a check in [Skip rows where actual type and attribute list type are different].

Notes