Data-Integration-Developer Sample Questions Answers

The parameters that are defined in File Delimited metadata are:

• Row separator: This parameter defines the character or string that separates each row of data in a delimited file. For example, a row separator can be a newline character (\n), a carriage return (\r), or a combination of both (\r\n).
• File path: This parameter defines the location and name of the delimited file that you want to read or write. You can browse your local system or enter a URL to specify the file path. You can also use context variables or global variables to make the file path dynamic.

To create a job consisting of two subjobs, A and B, and add a Joblet C with the intention of running it between A and B, you need to do the following steps:

• Design subjob A by adding components and links to it in the Designer workspace.
• Add a Start component to mark the beginning of subjob B and link it to subjob A using an OnSubjobOk trigger.
• Design subjob B by adding components and links to it after the Start component in the Designer workspace.
• Add a tJobletTriggerInput component to your Joblet C design and link it to other components in your Joblet using data flows or triggers.
• Add a tJobletTriggerOutput component to your Joblet C design and link it to other components in your Joblet using data flows or triggers.
• Drag your Joblet C from the Repository tree view to the Designer workspace between subjob A and subjob B.
• Link your Joblet C to subjob A using an OnComponentOk trigger from the last component of subjob A to the tJobletTriggerInput component of your Joblet C.
• Link your Joblet C to subjob B using an OnComponentOk trigger from the tJobletTriggerOutput component of your Joblet C to the Start component of subjob B.

The minimum requirements to orchestrate this are adding TRIGGER_INPUT and TRIGGER_OUTPUT components into C and linking A, B, and C using OnSubjobOk triggers. These are generic components that allow you to define triggers for your Joblet without depending on specific components. You do not need to add TRIGGER_INPUT and TRIGGER_OUTPUT components into A or B, as these are regular subjobs that can use any type of components or triggers. References: Talend Open Studio: Open-source ETL and Free Data Integration | Talend, [tJobletTriggerInput properties - 7.3], [tJobletTriggerOutput properties - 7.3], [Joblets - 7.3], [Triggers - 7.3]

To create an empty Joblet, you need to right-click on the Joblet Designs node in the Repository tree view and select Create Joblet option. This will open a dialog box whereyou can enter the name and description of your Joblet and select an icon for it. You can then design your Joblet by adding components and links to it in the Designer workspace.

You cannot create an empty Joblet by creating an empty job, then exporting it as a Joblet by right-clicking it in the Repository, creating an empty job and using the file menu to save it as Joblet, or right-clicking a space in the Designer and selecting refactor to Joblet. These methods are not available in Talend Studio and may cause errors or unexpected results. References: Talend Open Studio: Open-source ETL and Free Data Integration | Talend, [Joblets - 7.3]

Talend Studio provides two types of SQL templates: system SQL templates and user-defined SQL templates. SQL templates are predefined SQL queries that can be used in various components that execute SQL statements, such as tDBInput, tDBRow, tDBOutput, etc. System SQL templates are provided by Talend Studio and cover common SQL operations, such as creating, dropping, or altering tables, inserting, updating, or deleting data, etc. User-defined SQL templates are created by the user and can be customized according to specific needs. User-defined SQL templates can be created by using the SQL Templates view in Talend Studio and can be organized into categories and subcategories. There are no custom SQL templates orsystem-defined SQL templates in Talend Studio. References: Talend Open Studio: Open-source ETL and Free Data Integration | Talend, [SQL Templates - 7.3]

The tMysqlOutput component is used to write data into a MySQL database table. The Action on table parameter of this component allows you to specify what operation to perform on the table before loading data into it. The Action on table parameter supports the following operations:

• Drop table if exists and create: This operation drops the table if it already exists in the database and creates a new one with the same name and structure as defined in the schema.
• Create table: This operation creates a new table in the database with the name and structure as defined in the schema. If a table with the same name already exists, an error will be raised.
• Create table if does not exist: This operation creates a new table in the database with the name and structure as defined in the schema only if there is no table with the same name already existing in the database. If a table with the same name already exists, no action will be taken.

The Action on table parameter does not support the following operations:

• Replace: This is not an operation on the table, but on the data. The Replace parameter of the tMysqlOutput component allows you to specify whether to replace existing rows in the table with new rows based on a key attribute or to insert new rows only.
• Drop table: This is not an operation on the table, but on the database. The Drop table parameter of the tMysqlConnection component allows you to specify whether to drop the table after closing the connection or not. References: Talend Open Studio: Open-source ETL and Free Data Integration | Talend, [tMysqlOutput properties - 7.3], [tMysqlConnection properties - 7.3]

Trace Debug and Java Debug are two modes that allow you to debug your jobs in Talend Studio. Trace Debug mode allows you to trace each row processed by your job components and see the values of each column in each row. Java Debug mode allows you to debug your job code in Java or Perl and see the values of each variable or expression in your code.

The characteristics that distinguish Trace Debug from Java Debug are:

• Trace Debug mode allows row-by-row inspection of data flows, while Java Debug mode does not. Data flows are the links that show the data transfer between components in your job design workspace. In Trace Debug mode, you can see the data flow on each trace and inspect the values of each column for each row processed by your job. You can also use filters to display only the rows that match a condition or an expression. In Java Debug mode, you cannot see the data flow on each trace or inspect the values of each column for each row.
• Trace Debug mode supports breakpoints based on input data condition, while Java Debug mode does not. Breakpoints are points where the execution of your job pauses and waits for your action. You can use breakpoints to inspect your data or debug your logic at specific points of your job execution. In Trace Debug mode, you can set breakpoints on traces based on a condition or an expression that involves input data columns. For example, you can set a breakpoint to pause your job when a customer name contains a certain string or when a product price exceeds a certain value. In Java Debug mode, you can only set breakpoints on lines of code based on a condition or an expression that involves variables or expressions.

The characteristics that do not distinguish Trace Debug from Java Debug are:

• Both modes require a separate perspective. A perspective is a set of views and editors that are arranged in a specific way to support a specific task. In Talend Studio, you can switch between different perspectives, such as Integration, Debug, Profiling, etc. To use Trace Debug mode, you need to switch to the Debug perspective by clicking on the Open Perspective button and selecting Debug. To use Java Debug mode, you need to switch to the Java perspective by clicking on the Open Perspective button and selecting Java.
• Neither mode requires Java development experience. Although Java Debug mode allows you to debug your job code in Java or Perl, you do not need to have Java development experience to use it. You can use the graphical interface of Talend Studio to design your job components and properties without writing any code. You can also use the Code view to see the generated code of your job in Java or Perl and modify it if needed. However, you do not need to write any code from scratch or understand all the details of the code to use Java Debug mode. References: Talend Open Studio: Open-source ETL and Free Data Integration | Talend, [Trace Debug mode - 7.3], [Java Debug mode - 7.3]

You need to use the following code in a tJava component to write a nb_line variable:

int nb_line = (Integer)globalMap.get(“tFileInputDelimited_1_NB_LINE”);

This code retrieves the value of the global variable tFileInputDelimited_1_NB_LINE, which stores the number of rows processed by the tFileInputDelimited component, and assigns it to an integer variable named nb_line. You can then use this variable to print or manipulate the number of rows in your Job. Note that you need to use globalMap.get, not globalMap.put, to access the value of a global variable.

The generic Input component used for in a Joblet design is the tJobletInput component. This component is used to carry data into a Joblet from another component in the job that contains the Joblet. A Joblet is a reusable piece of a job that can be used in multiple jobs as a single component. A Joblet can have one or more input and output flows that connect it with other components in a job. To create these flows, you need to use generic input and output components, such as tJobletInput, tJobletOutput, tJobletTriggerInput, and tJobletTriggerOutput. These components allow you to define schemas and triggers for your Joblet without depending on specific components.

The tJobletInput component is not used for triggering a Joblet, triggering a subjob, or carrying data into a subjob. These are different concepts and functionalities in Talend Studio. A trigger is a link that activates a subjob or a component based on a condition or an event. A subjob is a part of a job that consists of one or more components connected by data flows or triggers. A subjob can be triggered by another subjob using triggers such as OnSubjobOk, OnSubjobError, Run if, etc. A subjob can also carry data into another subjob using data flows such as main, lookup, reject, etc. References: Talend Open Studio: Open-source ETL and Free Data Integration | Talend, [tJobletInput properties - 7.3], [Joblets - 7.3], [Triggers - 7.3]

The Sync columns button on the Basic settings tab of the Component view retrieves the schema from the input component connected in the Job and synchronizes it with the current component’s schema. This button is available for most of the components that have an input and an output schema, such as tJavaRow, tMap, tFileOutputDelimited, etc. However, this button does not retrieve and synchronize the output file schema with the input file schema for tFileOutputDelimited, as this component only has one output schema.

The Start component in a subjob triggers the execution of the next subjob in a sequential order. The Start component is used to define where a subjob begins and to link it with other subjobs within a job. The Start component has only one output link that can be connected to any other component in the same subjob or to another Start component in another subjob. When a subjob completes successfully, it sends an OnSubjobOk trigger to its Start component, which then activates the next subjob linked to it. The Final component, on the other hand, is used to define where a subjob ends and to perform some actions after its completion, such as sending anemail or logging a message. The Final component has no output link and does not trigger any other subjob. The Input component and any other component in a subjob do not trigger any other subjob by themselves, unless they are connected to a Start component through an output link or an OnComponentOk trigger. References: Talend Open Studio: Open-source ETL and Free Data Integration | Talend, [Start properties - 7.3], [Final properties - 7.3]

To reference the value of a context variable you defined, you can use the syntax context.variable_name, where variable_name is the name of the context variable. For example, if you have a context variable named path, you can reference its value by using context.path. You do not need to specify the context name (such as test or prod) or use parentheses or brackets around the variable name. References: Talend Data Integration — Software to Connect, Access, and Transform Data | Talend, [Contexts - 7.3]

The tMap component allows you to configure multiple input sources for your data transformation and mapping. The main input source is always placed on top of the tMap component and cannot be moved within it. The main input source provides the data flow that drives the processing of the tMap component. The lookup tables are placed below the main input source and can be reordered by using the up and down arrows on the toolbar. The order in which the lookup tables appear on the tMap component does not affect the functionality of the joins, as long as they are configured correctly with the appropriate join conditions and expressions. References: Talend Open Studio: Open-source ETL and Free Data Integration | Talend, [tMap properties - 7.3]

To identify execution times to verify the effectiveness of your changes, you can use one of these methods:

• Reading the time stamps from the execution console in the Run view. This method allows you to see the start and end time of each subjob and component in your job, as well as the total execution time of the job. You can also see the number of rows processed by each component and the status of the job (success or failure).
• Observing the execution times that annotate the flows in the Designer. This method allows you to see the execution time of each flow (main, lookup, reject, etc.) between components in your job. You can also see the number of rows processed by each flow and the throughput (rows per second) of each flow.

You cannot use these methods to identify execution times:

• Observing the execution time in the Code view. This method does not show you the execution time of your job or its components, but only the generated code of your job in Java or Perl. The Code view is useful for debugging or customizing your code, but not for measuring performance.
• Comparing time stamps in Trace Debug mode. This method does not show you the execution time of your job or its components, but only the values of eachcolumn for each row processed by your job. The Trace Debug mode is useful for tracing data quality or transformation issues, but not for measuring performance. References: Talend Open Studio: Open-source ETL and Free Data Integration | Talend, [Run view - 7.3], [Designer - 7.3], [Code view - 7.3], [Trace Debug mode - 7.3]