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.

Built-In: You create and store the
schema locally for this component only. Related topic: see
Talend Studio

User Guide.

Repository: You have already created
the schema and stored it in the Repository. You can reuse it in various projects and
Job designs. Related topic: see
Talend Studio

User Guide.

When the schema to be reused has default values that are integers or
functions, ensure that these default values are not enclosed within quotation marks. If
they are, you must remove the quotation marks manually.

You can find more details about how to verify default
values in retrieved schema in Talend Help Center (https://help.talend.com).

Table type

Select the type of the data model to be used for the table to be created. It can be
CQL (actually CQL3) or non-CQL (the legacy thrift-based API of Cassandra before CQL3).

This drop-down list is available only when the DB version
you are using is Cassandra 2.0.0. For the Cassandra versions later than 2.0.0, CQL becomes
the only model used by this component and so this list is no longer available.

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.

Use configuration file

Select this check box and in the field that is displayed, enter the path, or browse to
cassandra.yaml, the main configuration file for
Cassandra.

This way, this component can import and directly use the configuration from cassandra.yaml, which can contain many advanced Cassandra
properties, such as the properties for SSL encryption.

When you need to run your Job in different Cassandra environments, this feature allows
your Job to easily switch between the configurations.

For further information about this cassandra.yaml file,
see Cassandra configuration.

Keyspace

Type in the name of the keyspace into which you want to write the
SSTable.

Column family

Type in the name of the column family into which you want to write the
SSTable.

Partitioner

Select the partitioner which determines how data is distributed across
the Cassandra cluster.

• Random: default partitioner
  in Cassandra 1.1 and earlier.

• Murmur3: default partitioner
  in Cassandra 1.2.

• Order preserving: not
  recommended because it assumes keys are UTF8 strings.

For more information about the partitioner, see http://wiki.apache.org/cassandra/Partitioners.

Schema statement

Enter the statement to define the schema of the column family to be used or to be created
on the fly.

• This statement is a Cassandra prepared statement, which stores query results locally in
  the SSTable directory you define with this component before
  sending them to the server. For further information about the prepared statements, see Prepared statements.

• A Cassandra column family is a container for a collection of rows of records that have a
  similar kind. Its schema must contain strictly the same columns as the component schema you
  have defined, that is to say, the column names and the order of the columns in both the
  schemas must be identical.

For further information about a column family, see Standard column
family.

This field is available only when the version of your Cassandra database is later than
2.0.0. When it is 2.0.0, it is available only when you have selected CQL from the Table type drop-down
list.

Insert statement

Enter the statement to instruct how to write the data from the input flow into the columns
of the column family to be used.

This statement is a Cassandra prepared statement, which stores query results locally in
the SSTable directory you define with this component before
sending them to the server. For further information about the prepared statements, see Prepared statements.

This field is available only when the version of your Cassandra database is later than
2.0.0. When it is 2.0.0, it is available only when you have selected CQL from the Table type drop-down
list.

Column name comparator

Select the data type for the column names, which is used to sort
columns. This list is not available when the data model to be used is
CQL3.

For more information about the comparators, see http://www.datastax.com/docs/1.1/ddl/column_family#about-data-types-comparators-and-validators.

SSTable directory

Specify the local directory for the SSTable. Note that the complete
path to the SSTable will be the local directory appended by the
specified keyspace name and column family name.

For example, if you set the local directory to /home/talend/sstable, and specify testk as the keyspace name and testc as the column family name, the
complete path to the SSTable will be /home/talend/sstable/testk/testc/.

Buffer size

Specify what size the SSTable must reach before it is written into
Cassandra.

tStatCatcher Statistics

Select this check box to gather the Job processing metadata at the Job
level as well as at each component level.

Global Variables

ERROR_MESSAGE: the error message generated by the
component when an error occurs. This is an After variable and it returns a string. This
variable functions only if the Die on error check box is
cleared, if the component has this check box.

A Flow variable functions during the execution of a component while an After variable
functions after the execution of the component.

To fill up a field or expression with a variable, press Ctrl +
Space to access the variable list and choose the variable to use from it.

For further information about variables, see
Talend Studio

User Guide.

Usage rule

This component always needs an incoming link.