tCassandraLookupInput - 6.1

Talend Components Reference Guide

EnrichVersion
6.1
EnrichProdName
Talend Big Data
Talend Big Data Platform
Talend Data Fabric
Talend Data Integration
Talend Data Management Platform
Talend Data Services Platform
Talend ESB
Talend MDM Platform
Talend Open Studio for Big Data
Talend Open Studio for Data Integration
Talend Open Studio for Data Quality
Talend Open Studio for ESB
Talend Open Studio for MDM
Talend Real-Time Big Data Platform
task
Data Governance
Data Quality and Preparation
Design and Development
EnrichPlatform
Talend Studio

Warning

The streaming version of this component is available in the Palette of the studio on the condition that you have subscribed to Talend Real-time Big Data Platform or Talend Data Fabric.

Function

tCassandraInput allows you to read data from a Cassandra keyspace and send data in the Talend flow.

Purpose

tCassandraInput allows you to extract the desired data from a standard or super column family of a Cassandra keyspace so as to apply changes to the data.

It passes on the extracted data to tMap in order to provide the lookup data to the main flow. It must be directly connected to a tMap component and requires this tMap to use Reload at each row or Reload at each row (cache) for the lookup flow.

Mapping tables between Cassandra type and Talend data type

The first of the following two tables presents the mapping relationships between Cassandra type with Cassandra's new API, Datastax and Talend data type.

If the Cassandra version you are using with the Studio is older than 2.0, or if you select the Hector API in the component to use with Cassandra 2.0, see the second table.

Cassandra Type

Talend Data Type

Ascii

String; Character

BigInt

Long

Blob

Byte[]

Boolean

Boolean

Counter

Long

Inet

Object

Int

Integer; Short; Byte

List

List

Map

Object

Set

Object

Text

String; Character

Timestamp

Date

UUID

String

TimeUUID

String

VarChar

String; Character

VarInt

Object

Boolean

Boolean

Float

Float

Double

Double

Decimal

BigDecimal

The following table presents the mapping relationships between Cassandra type with the Hector API and Talend data type.

Cassandra Type

Talend Data Type

BytesType

byte[]

AsciiType

String

UTF8Type

String

IntegerType

Object

Int32Type

Integer

LongType

Long

UUIDType

String

TimeUUIDType

String

DateType

Date

BooleanType

Boolean

FloatType

Float

DoubleType

Double

DecimalType

BigDecimal

tCassandraLookupInput properties in Spark Streaming Jobs

Component family

Databases / Cassandra

 

Basic settings

Property type

Either Built-In or Repository.

Built-In: No property data stored centrally.

Repository: Select the repository file where the properties are stored.

 

DB Version

Select the Cassandra version you are using.

 

Host

Hostname or IP address of the Cassandra server.

 

Port

Listening port number of the Cassandra server.

 

Required authentication

Select this check box to provide credentials for the Cassandra authentication.

 

Username

Fill in this field with the username for the Cassandra authentication.

 

Password

Fill in this field with the password for the Cassandra authentication.

To enter the password, click the [...] button next to the password field, and then in the pop-up dialog box enter the password between double quotes and click OK to save the settings.

 

Schema and Edit Schema

A schema is a row description. It defines the number of fields (columns) to be processed and passed on to the next component. The schema is either Built-In or stored remotely in the Repository.

Click Edit schema to make changes to the schema. If the current schema is of the Repository type, three options are available:

  • View schema: choose this option to view the schema only.

  • Change to built-in property: choose this option to change the schema to Built-in for local changes.

  • Update repository connection: choose this option to change the schema stored in the repository and decide whether to propagate the changes to all the Jobs upon completion. If you just want to propagate the changes to the current Job, you can select No upon completion and choose this schema metadata again in the [Repository Content] window.

The schema of this component dose not support the Object type and the List type.

 

Keyspace

Type in the name of the keyspace from which you want to read data.

 

Column family

Type in the name of the column family from which you want to read data.

 

Query type and Query

Enter your DB query paying particularly attention to properly sequence the fields in order to match the schema definition.

The schema of the main flow to tMap is available to use to construct the SQL statement in the current component.

Note that the result set from this lookup component must be filtered to only return rows that match the expected join key in tMap.

Advanced settings

Connection pool

In this area, you configure the connection pool used to control the number of connections that stay open simultaneously. Generally speaking, the default values given to the following connection pool parameters are good enough for most use cases.

  • Max total number of connections: enter the maximum number of connections (idle or active) that are allowed to stay open simultaneously.

    The default number is 8. If you enter -1, you allow unlimited number of open connections at the same time.

  • Max waiting time (ms): enter the maximum amount of time at the end of which the response to a demand for using a connection should be returned by the connection pool. By default, it is -1, that is to say, infinite.

  • Min number of idle connections: enter the minimum number of idle connections (connections not used) allowed in the connection pool.

  • Max number of idle connections: enter the maximum number of idle connections (connections not used) allowed in the connection pool.

 

Evict connections

Select this check box to define criteria to destroy connections in the connection pool. The following fields are displayed once you have selected it.

  • Time between two eviction runs: enter the time interval (in milliseconds) at the end of which the component checks the status of the connections and destroys the idle ones.

  • Min idle time for a connection to be eligible to eviction: enter the time interval (in milliseconds) at the end of which the idle connections are destroyed.

  • Soft min idle time for a connection to be eligible to eviction: this parameter works the same way as Min idle time for a connection to be eligible to eviction but it keeps the minimum number of idle connections, the number you define in the Min number of idle connections field.

Usage in Spark Streaming Jobs

In a Talend Spark Streaming Job, it is used as a start component and requires an output link. The other components used along with it must be Spark Streaming components, too. They generate native Spark code that can be executed directly in a Spark cluster.

This component should use one and only one tCassandraConfiguration component present in the same Job to connect to Cassandra. More than one tCassandraConfiguration components present in the same Job fail the execution of the Job.

This component, along with the Spark Streaming component Palette it belongs to, appears only when you are creating a Spark Streaming Job.

Note that in this documentation, unless otherwise explicitly stated, a scenario presents only Standard Jobs, that is to say traditional Talend data integration Jobs.

Log4j

If you are using a subscription-based version of the Studio, the activity of this component can be logged using the log4j feature. For more information on this feature, see Talend Studio User Guide.

For more information on the log4j logging levels, see the Apache documentation at http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/Level.html.

Spark Connection

You need to use the Spark Configuration tab in the Run view to define the connection to a given Spark cluster for the whole Job. In addition, since the Job expects its dependent jar files for execution, one and only one file system related component from the Storage family is required in the same Job so that Spark can use this component to connect to the file system to which the jar files dependent on the Job are transferred:

This connection is effective on a per-Job basis.

Related scenarios

No scenario is available for the Spark Streaming version of this component yet.