tELTGreenplumMap

tELTGreenplumMap properties

The three ELT Greenplum components are closely related, in terms of their operating
conditions. These components should be used to handle Greenplum DB schemas to generate
Insert statements, including clauses, which are to be executed in the DB output table
defined.

Component family	ELT/Map/Greenplum
Function	Helps you to build the SQL statement graphically, using the table provided as input.
Purpose	Uses the tables provided as input, to feed the parameter in the built statement. The statement can include inner or outer joins to be implemented between tables or between one table and its aliases.
Basic settings	Use an existing connection	Select this check box and in the Component List click the relevant connection component to reuse the connection details you already defined. Note When a Job contains the parent Job and the child Job, if you need to share an existing connection between the two levels, for example, to share the connection created by the parent Job with the child Job, you have to: In the parent level, register the database connection to be shared in the Basic settings view of the connection component which creates that very database connection. In the child level, use a dedicated connection component to read that registered database connection. For an example about how to share a database connection across Job levels, see Talend Studio User Guide.
	ELT Greenplum Map Editor	The ELT Map editor allows you to define the output schema and make a graphical build of the SQL statement to be executed. The column names of schema can be different from the column names in the database.
	Style link	Select the way in which links are displayed. Auto: By default, the links between the input and output schemas and the Web service parameters are in the form of curves. Bezier curve: Links between the schema and the Web service parameters are in the form of curve. Line: Links between the schema and the Web service parameters are in the form of straight lines. This option slightly optimizes performance.
	Property type	Either Built-in or Repository. Since version 5.6, both the Built-In mode and the Repository mode are available in any of the Talend solutions.
		Built-in: No property data stored centrally.
		Repository: Select the Repository file where Properties are stored. The following fields are pre-filled in using fetched data.
	Host	Database server IP address.
	Port	Listening port number of DB server.
	Database	Name of the database.
	Username and Password	DB user authentication data. 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.
Advanced settings	Additional JDBC parameters	Specify additional connection properties for the DB connection you are creating. This option is not available if you have selected the Use an existing connection check box in the Basic settings.
	tStatCatcher Statistics	Select this check box to gather the Job processing metadata at a Job level as well as at each component level.
Dynamic settings	Click the [+] button to add a row in the table and fill the Code field with a context variable to choose your database connection dynamically from multiple connections planned in your Job. This feature is useful when you need to access database tables having the same data structure but in different databases, especially when you are working in an environment where you cannot change your Job settings, for example, when your Job has to be deployed and executed independent of Talend Studio. The Dynamic settings table is available only when the Use an existing connection check box is selected in the Basic settings view. Once a dynamic parameter is defined, the Component List box in the Basic settings view becomes unusable. For more information on Dynamic settings and context variables, see Talend Studio User Guide.
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	tELTGreenplumMap is used along with tELTGreenplumInput and tELTGreenplumOutput. Note that the Output link to be used with these components must correspond strictly to the syntax of the table name. Note Note that the ELT components do not handle actual data flow but only schema information.

Adding where and other clauses

You can also restrict the Select statement based on a Where clause and/or other clauses such
as Group By, Order By, etc. by clicking the Add filter
row button at the top of the output table in the map editor.

To add a restriction based on a Where clause, click the Add
filter row button and select Add a WHERE
clause from the popup menu.

To add a restriction based on Group By, Order By etc., click the Add filter row button and select Add an
other(GROUP…) clause from the popup menu.

Make sure that all input components are linked correctly to the ELT Map component to
be able to implement all inclusions, joins and clauses.

Scenario: Mapping data using a simple implicit join

In this scenario, a tELTGreenplumMap component is
deployed to retrieve the data from the source table employee_by_statecode, compares its statecode column against the table statecode, and then maps the desired columns from the two tables to the
output table employee_by_state.

Before the Job execution, the three tables, employee_by_statecode, statecode and
employee_by_state look like:

Dropping components

Drop tGreenplumConnection, tELTGreenplumInput (two), tELTGreenplumMap, tELTGreenplumOutput, tGreenplumCommit, tGreenplumInput and tLogRow
from the Palette onto the workspace.
Rename tGreenplumConnection as connect_to_greenplum_host, two tELTGreenplumInput components as employee+statecode and statecode, tELTGreenplumMap
as match+map, tELTGreenplumOutput as map_data_output, tGreenplumCommit as commit_to_host, tGreenplumInput as read_map_output_table and tLogRow as show_map_data.
Link tGreenplumConnection to tELTGreenplumMap using an OnSubjobOk trigger.

Link tELTGreenplumMap to tGreenplumCommit using an OnSubjobOk trigger.

Link tGreenplumCommit to tGreenplumInput using an OnSubjobOk trigger.
Link tGreenplumInput to tLogRow using a Row >
Main connection.

The two tELTGreenplumInput components and
tELTGreenplumOutput will be linked to
tELTGreenplumMap later once the
relevant tables have been defined.

Configuring the components

Double-click tGreenplumConnection to
open its Basic settings view in the
Component tab.

In the Host and Port fields, enter the context variables for the Greenplum
server.

In the Database field, enter the context
variable for the Greenplum database.

In the Username and Password fields, enter the context variables for the
authentication credentials.

For more information on context variables, see Talend Studio User Guide.
Double-click employee+statecode to open
its Basic settings view in the Component tab.

In the Default table name field, enter
the name of the source table, namely employee_by_statecode.

Click the […] button next to the
Edit schema field to open the schema
editor.

Click the [+] button to add three
columns, namely id,
name and statecode, with the
data type as INT4, VARCHAR, and INT4 respectively.

Click OK to close the schema
editor.

Link employee+statecode to tELTGreenplumMap using the output employee_by_statecode.
Double-click statecode to open its
Basic settings view in the Component tab.

In the Default table name field, enter
the name of the lookup table, namely statecode.
Click the […] button next to the
Edit schema field to open the schema
editor.

Click the [+] button to add two columns,
namely state and
statecode, with the data type as VARCHAR and INT4 respectively.

Click OK to close the schema
editor.

Link statecode to tELTGreenplumMap using the output statecode.
Click tELTGreenplumMap to open its
Basic settings view in the Component tab.

Select the Use an existing connection
check box.
Click the […] button next to the
ELT Greenplum Map Editor field to open
the map editor.
Click the [+] button on the upper left
corner to open the table selection box.

Select tables employee_by_statecode and
statecode in sequence and click
Ok.

The tables appear on the left panel of the editor.
On the upper right corner, click the [+]
button to add an output table, namely employee_by_state.

Click Ok to close the map editor.
Double-click tELTGreenplumOutput to open
its Basic settings view in the Component tab.

In the Default table name field, enter
the name of the output table, namely employee_by_state.
Click the […] button next to the
Edit schema field to open the schema
editor.

Click the [+] button to add three
columns, namely id,
name and state, with the data
type as INT4, VARCHAR, and VARCHAR
respectively.

Click OK to close the schema
editor.

Link tELTGreenplumMap to tELTGreenplumOutput using the table output
employee_by_state.

Click OK on the pop-up window below to
retrieve the schema of tELTGreenplumOutput.

Now the map editor’s output table employee_by_state shares the same schema as that of
tELTGreenplumOutput.
Double-click tELTGreenplumMap to open the
map editor.

Drop the column statecode from table
employee_by_statecode to its
counterpart of the table statecode,
looking for the records in the two tables that have the same statecode values.

Drop the columns id and name from table employee_by_statecode as well as the column statecode from table statecode to their counterparts in the output table
employee_by_state.

Click Ok to close the map editor.
Double-click tGreenplumInput to open its
Basic settings view in the Component tab.

Select the Use an existing connection
check box.

In the Table name field, enter the name
of the source table, namely employee_by_state.

In the Query field, enter the query
statement, namely "SELECT * FROM "employee_by_state"".
Double-click tLogRow to open its
Basic settings view in the Component tab.

In the Mode area, select Table (print values in cells of a table for a
better display.

Executing the Job

Press Ctrl+S to save the Job.
Press F6 to run the Job.

As shown above, the desired employee records have been written to the
table employee_by_state, presenting
clearer geographical information about the employees.

Related scenarios

For related scenarios, see:

Scenario 1: Aggregating table columns and filtering.
Scenario 2: ELT using an Alias table.
A related scenario using subquery: Scenario: Mapping data using a subquery.

Document get from Talend https://help.talend.com

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Docs 5.x

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tELTGreenplumMap – Docs for ESB 5.x