Microsoft is a software giant that offers various beneficial products and services to organizations and professionals. Also, many renowned companies trust the Microsoft technology stack to accelerate their business operations and achieve better growth. You might be thinking about what Microsoft's technology stack is?
Well, it is a collection of technologies developed by the tech mogul to help organizations and developers create efficient and top-quality software products. Microsoft technology stack involves everything in one place, from coding languages, development platforms, and backend databases to cloud and business applications.
One of the most popular tools in the Microsoft technology stack is Microsoft SQL Server. Microsoft designed this tool especially for managing and utilizing data effectively. In addition, Microsoft SQL Server supports multiple add-ons. Therefore, along with the relational database engine, Microsoft SQL Server also manages different aspects of data analytics, such as business intelligence, analysis and reporting, and data integration.
Through this article, you will get introduced to the fundamental services offered by the Microsoft SQL Server (MSSQL) suite. In addition, we will discuss detailed answers to frequently asked SSIS interview questions.
Services Offered by Microsoft SQL Server
The Microsoft SQL Server (MSSQL) suite, along with a relational database engine for maintaining data in the form of rows and columns, has three additional services that are as follows:
1. SQL Server Integration Services (SSIS)
SSIS is a platform used for importing and exporting data from the relational database. As the data moves in and out of the database, it is also called a data movement tool. In addition, organizations and companies use SSIS to design and develop ETL processes.
Moreover, SSIS allows us to extract or use data from heterogeneous sources, such as external databases, Excel sheets, documents, and so on. After extracting the required data, we can transform it by sorting, filtering, or merging, and finally, loading the transformed data into its desired place.
2. SQL Server Analysis Services (SSAS)
SSAS possesses data mining and OLAP features. It is globally used by companies and businesses to analyze and drive meaningful insights of data spread across various databases.
3. SQL Server Reporting Services (SSRS)
As its name suggests, SSRS is designed for developing and deploying different types of paginated reports. In addition, this tool comes with the ability to report on data present in the database and represent it in complex visualizations or even simple charts. Therefore, we can call SSRS a reporting tool.
50 Best SSIS Interview Questions and Answers
An SSIS developer is responsible for managing and maintaining data integration for companies or organizations. If you wish to become an SSIS developer, you must hold a bachelor’s degree in computer science.
Moreover, if you are a fresher, you should opt for Microsoft’s SSIS Certification. This certification is ideal for ETL developers and data warehouse developers. Additionally, becoming an SSIS developer requires you to appear for an interview. Many freshers may have no idea about the questions that an interviewer may ask.
If you are among those freshers, you are at a perfect place. All these questions are categorized into three categories, namely basic SSIS interview questions, intermediate SSIS interview questions, and advanced SSIS interview questions. The below-mentioned SSIS interview questions will aid you in preparing effectively for your next interview:
Basic SSIS Interview Questions
1. Explain SSIS.
Answer: SSIS is an acronym for SQL Server Integration Services. It is one of the most vital services of the Microsoft SQL Server (MSSQL) suite. Organizations and businesses use SSIS to perform a broad spectrum of migration tasks. As SSIS performs data migration, it is called a data movement tool. SSIS is a comprehensive platform that helps users develop high-grade data transformation and data integration solutions.
Moreover, the SSIS platform performs various tasks, such as loading data warehouses, cleaning data, copying or downloading files, and so on, to resolve intricate business issues. Additionally, SSIS can retrieve and transform data from multiple sources, such as flat files, various databases, XML data files, Excel files, and many other sources. After extracting and transforming the data, SSIS then loads it into several destinations.
2. Tell me something about the SSIS package.
Answer: The SSIS package is a well-organized and consistent set of components, such as data flow elements, event handlers, connections, variables, control flow elements, and configurations. We can congregate all these components in the SSIS package together either programmatically or by using SSIS’s graphical design tools. The SSIS Package Store, the SQL Server, or the file system can store the developed packages.
In addition, the first package designed is empty. We need to add one or more data flows, optionally, and control flow mandatorily. A package with a control flow and data flow forms a basic package. However, we can add extra characteristics, like variables, parameters, and so on, to expand the package’s features.
3. Explain different components of the SSIS package.
Answer: The SSIS package consists of five distinct components that are as follows:
- Control Flow - Control flow is considered the brain of the SSIS package. It maintains tasks and containers. In addition, it helps us to arrange and manage other components’ order of execution.
- Data Flow - Data flow is the core component of the SSIS package. The SSIS platform extracts data from various sources, transforms the data, and loads it into target places.
- Package Explorer - This component provides a single view for all elements present in a package.
- Event Handlers - This component helps to manage the task of sending emails, messages, and so forth.
- Parameters - Parameters are analogous to variables. They are the values that are to be passed to a function for starting a package.
4. What do you understand about the term Solution Explorer?
Answer: In SSIS, a Solution Explorer is a window or a screen that displays all the developed SSIS packages. In addition, this window consists of project parameters, project connection managers, and miscellaneous files required for the project.
5. Define data flow in SSIS.
Answer: Organizations primarily use the SSIS platform for carrying out migration tasks, which involve data flow. Therefore, data flow is simply the movement of data from the heterogeneous sources to the desired target places.
6. Explain the term ‘task’ in SSIS.
Answer: One of the most critical components of the SSIS package, called control flow, stores tasks, and containers. A task in SSIS is similar to any method or function used in programming languages. Therefore, a task is a small section of work in SSIS.
7. List out different kinds of files or connections supported by SSIS.
Answer: SSIS supports six distinct kinds of files or connections, and they are:
- XML
- Flat files
- Open Database Connectivity (ODBC)
- Excel
- .net SQLClient
- Object Linking and Embedding Database (OLEDB)
8. Define containers in SSIS.
Answer: The control flow component of the SSIS package stores tasks and containers. Objects that provide services and functionalities to the control flow’s tasks and structure to SSIS packages are known as containers. They are responsible for grouping relevant tasks together and converting them into a unit of work.
9. Explain Precedence Constraint.
Answer: Precedence Constraint is one of the most helpful functionalities of the SSIS package. There are several tasks and workflows in the SSIS package. As a result, it becomes challenging to implement all tasks simultaneously. Therefore, Precedence Constraint helps the SSIS package determine the logical order or sequence of tasks in which they should be executed.
10. Define variables, and list out their types in SSIS.
Answer: The SSIS package and its components, like tasks, event handlers, and containers, use values at run-time. These values are stored by variables. In addition, when constraint definitions involve expressions for arranging tasks for execution, the precedence constraint uses variables.
System variables and user-defined variables are two distinct kinds of variables in SSIS. Variables defined by developers while developing an SSIS package are called user-defined variables. On the contrary, variables that are specified by Integration Services are known as system variables. We cannot create new system variables but develop as many user-defined variables as an SSIS package requires.
11. Explain checkpoint in SSIS.
Answer: A checkpoint is a point of failure where an SSIS package restarts. If an SSIS package executes or runs without any failure, there is no need for the checkpoint file, and it is deleted. Otherwise, the package resumes the execution from the point where it failed to run.
In addition, the checkpoint file is an XML file consisting of details about the SSIS package execution. It stores information about completed tasks and the values of an SSIS package’s variables. The checkpoint file is maintained to restore an SSIS package’s state when it fails to run.
12. What are connection managers?
Answer: When we collect data from different sources and load them into several target places, connection managers are helpful. Connection managers help us configure a connection between external and heterogeneous data sources and the actual SSIS.
13. Define breakpoints in SSIS.
Answer: Breakpoints in SSIS are similar to breakpoints used in programming languages. Developers insert breakpoints in the program to pause its execution and start debugging it. However, programmers debug a program to verify the values of variables and check whether the program follows the logic.
In SSIS, we can add breakpoints in an SSIS package and a control flow task. When an SSIS package encounters a breakpoint, it pauses its execution. Breakpoints in SSIS are used during the development of a package or while troubleshooting it.
14. Explain the term ‘event logging.’
Answer: Event logging in SSIS allows us to log the events of a particular SSIS package or a task. The use of event logging is advantageous when we troubleshoot an SSIS package. In addition, it helps us know the package’s performance.
15. What do you know about the logging mode property?
Answer: All SSIS packages and their corresponding tasks possess a property. This property is called LoggingMode. The LoggingMode property supports three different values:
- Disabled: It disables a particular component’s logging.
- Enabled: It enables a specific component’s logging.
- Use Parent Settings: It uses a component’s parent settings.
16. What is a data flow buffer?
Answer: The data flow in SSIS uses a memory buffer to maintain the data flow between the source and target destinations. This memory buffer is known as a data flow buffer. Moreover, the data flow buffer is a type of in-memory virtual table that maintains data.
17. Explain the SSIS conditional split transformation.
Answer: The conditional split transformation in SSIS is similar to the CASE decision structure used in programming languages. It checks a specific condition and directs input data rows to particular outputs based on that condition. In addition, if an input row does not match the condition, the conditional split transformation directs it to the default output.
18. What are the different kinds of data viewers?
Answer: SSIS supports four distinct kinds of data views. These data viewers are as explained below:
- Grid displays data columns in the grid style.
- The histogram represents column data in the histogram model. In addition, the histogram model works with one data column at a time.
- Scatter Plot represents numeric data in the form of (x,y).
- Column Chart displays column data in the column chart. Like the histogram model, a column chart also supports one data column at one time.
19. List out all possible locations to save an SSIS package.
Answer: There are three different locations available to maintain SSIS packages. They are listed below:
- Package Store
- SQL Server
- File System
20. Name the type of containers for which we cannot save the checkpoint data.
Answer: We cannot save the checkpoint data for two different types of containers, namely For Loop and For Each Loop containers.
Intermediate SSIS Interview Questions
21. What does the Event Handlers Tab do in SSIS?
Answer: When an SSIS package is running, containers and tasks in a control flow raise events. To answer these events when they are raised, we use Event Handlers. Therefore, the Event Handlers in SSIS are responsible for configuring workflows to respond to different SSIS package events.
The Event Handlers tab’s design surface helps us create new event handlers in SSIS Designer. In addition, this tab also consists of the connection managers area, allowing us to develop and modify connection managers. Event handlers use these connection managers to connect data sources and servers.
22. Describe the process for enabling logging to an SSIS package.
Answer: We can log in to an SSIS package by following the steps mentioned below:
1. Firstly, open the Integration Services project that contains the desired package in the SQL Data Server Tool.
2. Go to the SSIS menu and hit the ‘ Logging ’ option.
3. There is a Provider Type list to select the desired log provider. Select the one and click on the ‘ Add ’ option.
4. The next action is to develop a connection manager for the log provider. Go to the Configuration column and either click < New Connection > or choose the existing connection manager. Make sure to select a suitable connection manager.
For instance:
-
- Choose a File Connection Manager for Text files, XML files, and SQL Server Profiler.
- Select an OLE DB Connection Manager for SQL Server.
- If there is a Windows Event Log, SSIS automatically creates a connection manager.
5. To insert each log in an SSIS package, repeat steps c and d.
6. This step is optional to perform. We can select logs to be used for package-level logging and package-level checkbox.
7. Later, click on the Details tab. To log all log entries, we need to click on Events . On the other hand, if we wish to select a single log entry, clear Events .
8. Further, if we need to specify certain information to log in, we must click on the Advanced tab. All information is logged by default.
9. To save the information, hit the Save button. Later a dialogue box appears, where we need to locate the folder to save the logging configuration. For a new log configuration, add the file name. Lastly, click Save , and then hit the OK button.
10. Finally, go to the File menu and click the Save Selected Items option.
23. If there is an SSIS package failure, how would you convey it to other members?
Answer: There are two different approaches to notifying staff members about the package failure. One method is to add a Send Mail Task in the event handlers inside an SSIS package. Alternatively, you can use the SQL Agent to set an alert regarding the package failure when the package starts running.
24. Explain the deployment process of an SSIS package.
Answer: There are two methods used for the deployment of an SSIS package. The first is to run manifest files and determine which location out of the two - SQL Server or File System, to choose. The second method to deploy the package is to import an SSIS package from SSMS into File System or SQL Server.
25. How to perform the incremental load?
Answer: In SSIS, the principal goal of using incremental loads is to maintain the data between two systems in a synchronized manner. Alternatively, incremental loads in SSIS imply comparing the target and the source tables using Timestamp or Date Stamp. When the source data is repeatedly loaded into the destination, the incremental load is used.
To implement the incremental load, the source table should contain the Timestamp column, and we must store the timestamp of the last ETL. Moreover, if the source table contains new records, we must add them to the target table. Similarly, if the source table’s values are updated, we must also update them in the target table.
26. List out and explain the Data Flow’s components in SSIS?
Answer: SSIS gathers data from multiple sources, transforms the data using various methods, like filtering, cleansing, and sorting, and then loads the transformed data into target locations. Therefore, Source, Transformation, and Destination are three different SSIS data flow components.
27. State some best practices for using SSIS.
Answer: Some of the best tips to use SQL Server Integration Services efficiently are as follows:
- Ensure to carry out all SSIS transformations in memory, as SSIS is an in-memory pipeline.
- Always optimize destination locations, data source, and lookup transformations.
- Make sure to design a well-structured plan for resource utilization.
- Avoid using default buffer settings.
- Remember to avoid blocking transformations and logged operations.
- Try not to use OLE DB command transformation.
28. How to terminate a forever-running SSIS package?
Answer: Stopping a forever-running SSIS package depends upon whether we are using the SQL Agent or the SSIS catalog. If we opt for the SSIS catalog, we can stop the forever-running SSIS package using the stop operation stored procedure and Active Operations window. With the SQL Agent, we can stop the forever-running SSIS package by killing it with T-SQL .
29. State the features of SSIS.
Answer: Some key characteristics of SSIS are:
- SSIS has the ability to integrate data smoothly from heterogeneous sources.
- It enhances the quality of data by performing data cleansing and data profiling.
- SSIS can seamlessly integrate with other Microsoft SQL programs.
- It incorporates graphical tools and has an improved studio environment.
- SSIS implements high-speed data integration effectively and quickly.
- It supports data mining queries and workflow functionalities, like FTP.
- SSIS consists of data source connectors and APIs for object modeling.
30. List out the benefits and pitfalls of SSIS.
Answer: Advantages of SSIS are:
- One of the most significant benefits of SSIS is that it can manage data from multiple sources in the same package.
- It supports various protocols, such as HTTP and FTP.
- In addition, it offers the transformation feature.
- SSIS packages are easier to configure and maintain.
- SSIS is rigorously integrated with SQL Server and Microsoft Visual Studio.
- It is ideal to use for merging data from heterogeneous sources, intricate transformations, and multi-step operations.
- SSIS supports loading data from the source to different target locations parallelly.
Disadvantages of SSIS are:
- We need Management Studio to observe the SSIS package execution results.
- If we wish to run several SSIS packages parallelly, it may cause an issue because running multiple packages simultaneously requires more memory. Therefore, we may experience memory allocation issues between SSIS and SQL.
- Another major disadvantage is that SQL will run quicker and faster than SSIS. Therefore, we need to ensure that SSIS and SQL both get enough processors to run.
31. Can you explain Execute SQL Task in SSIS?
Answer: The Execute SQL Task in SSIS executes SQL statements or stored procedures from an SSIS package. This can either be a single SQL statement or multiple SQL statements running sequentially. We can use the Execute SQL Task for the following purposes:
- Create, alter, and drop database objects, such as tables and views.
- Truncate a table or view in preparation for inserting data.
- Run stored procedures.
- Recreate facts and dimension tables before inserting data into them.
32. Differentiate Execute TSQL Task and Execute SQL Task.
Answer: Execute TSQL Task is analogous to the Execute SQL Task. The only difference is that the Execute TSQL Task requires less memory, while Execute SQL Task consumes a lot of memory. In terms of performance, Execute TSQL Task is faster than Execute SQL Task. Moreover, Execute SQL Task supports parameterized queries and multiple types of connections. On the flip side, Execute TSQL Task does not support parameterized queries and supports only ADO.net connection.
33. Can you explain what a manifest file is?
Answer: We can define a manifest file as a utility containing information that we can use for deploying SSIS packages using the file system wizard and database of SQL Server.
34. What do you know about lookup transformation in SSIS?
The Lookup Transformation in SSIS is used to compare the source and destination data. It sorts the matched and unmatched data from the source and destination into two different destinations.
35. What do you understand about the lookup cache mode?
Answer: The SSIS Lookup Transformation utilizes the cache mode to determine how the data present in it is cached at runtime.
36. Can you state different lookup cache modes in SSIS?
Answer: There are three different lookup cache modes in SSIS, namely full cache mode, partial cache mode, and no cache mode.
- Full Cache Mode: In this mode, Lookup Transformation will read all the data once from the source into the Cache. Later, it will look up each record from the Source against the Lookup Table. If it finds matches, it loads those records in the Lookup Match Output and unmatched records in the Lookup No Match Output.
- Partial Cache Mode: In this mode, Lookup Transformation will read each record from the Source into the Cache. Later, it will look up that record from the Source against the Lookup Table. If it finds matches, it stores them in the Cache itself for further use and loads unmatched records in the Lookup No Match Output.
- No Cache Mode: In this mode, Lookup Transformation will not use cache. Instead, it will directly read records from the Source and lookup those records against the Lookup Table. If it finds matches, it loads those records in the Lookup Match Output and unmatched records in the Lookup No Match Output.
37. What are process bytes in SSIS?
Answer: Process bytes in SSIS represent the amount of memory the integration services are using currently. This memory cannot be shared with other processes.
38. Can you explain the Bulk Insert Task in SSIS?
Answer: When we need to copy large amounts of data into SQL Server tables or views, we use the Bulk Insert Task. It can transfer data from any text file to SQL Server tables or views. In addition, if the destination table or view contains data, the Bulk Insert Task appends new data to the existing data.
39. Do you know about the types of errors in SSIS?
Answer: There are two types of errors in SSIS that are as follows:
- Truncation: A truncation is a less series error. It may generate values that might be useful or desirable.
- Error: An error represents the failure of an SSIS component and generates a NULL result. Errors may result in the data conversion error or expressions evaluation error.
40. Why are SSIS packages preferred over stored procedures?
Answer: The following are the reasons for choosing SSIS packages over stored procedures:
- SSIS packages can handle complex transformation processes that involve slow-changing dimensions.
- They efficiently manage memory and provide better performance.
Advanced SSIS Interview Questions
41. Explain the SSIS catalog.
Answer: The SSIS catalog is a database that stores all the deployed SSIS packages and manages them effectively.
42. What do you know about SSIS expressions?
Answer: SSIS expressions consists of operators, literals, identifiers, and symbols. The most common use of SSIS expressions is to filter the necessary data depending on the specified conditions. We can use SSIS expressions with loops, conditions, and dynamic connections.
43. Enumerate the tasks of the SSIS integration process.
Answer: The following are some typical tasks in the SSIS integration process:
- Execute SQL Task - Implements SQL statements concerning a relational database.
- Execute Package Task - Calls all other packages in the same project.
- Data Flow Task - Retrieves data from heterogeneous sources, transforms it, and loads it into the desired place.
- Execute Process Task - Implements batch scripts or runs an application as SSIS.
- Analysis Service Processing Task - Processes a tabular model’s or SSAS cube’s objects.
- Script Task - Enables us to develop the code using the .NET framework .
- File System Task - Carries out various file system tasks, such as renaming, moving, deleting files, and changing the directory of the files.
- FTP Task - Carries out actions on files and folders.
44. What do you understand about merge and union all transformations?
Answer:
Merge: Merge transformation merges two different sources into a single output. This transformation is useful to break the data flow path and create a separate error path. Once the error is handled, we can merge it into the main data flow.
Union All: Union All transformation merges the data from all the sources into a single output.
45. Define the task host container.
Answer: The task host container stores a single task and is the default container in SSIS. This container provides services and functionalities to a task in a control flow. It enables us to extend variables and event handles to the task level. Moreover, in SSIS designer, the task host is not configured separately. Instead, it is configured when we set the properties of the task that it stores.
46. Define the sequence container.
Answer: The sequence container defines the control flow that is the subset of the package’s control flow. It divides a package into multiple separate control flows, where each control flow consists of one or more tasks and containers.
47. What is the foreach loop container?
Answer: The foreach loop container uses an enumerator to execute a control flow again and again. The primary aim of foreach loop containers is to repeat tasks for every element present in a collection.
48. Define the for loop container.
Answer: This type of container helps us to develop a loop in the package. In other words, the for loop container initializes expressions and executes them until they produce a ‘false’ as their results. Therefore, it is similar to the for-loop statement used in programming languages.
49. Is it possible to schedule SSIS packages?
Answer: Yes, it is possible to schedule SSIS packages at any time as required. We can schedule SSIS packages using SQL Server Agent.
50. What is data profiling in SSIS?
Answer: Data profiling is a significant task in SSIS for assessing the quality of the data sources. It is the process of analyzing data sources to obtain information, such as whether the data is ready to use and where to use it.
Conclusion
SSIS is one of the three components of Microsoft SQL Server (MSSQL). In addition, it is a significant part of Microsoft's Business Intelligence Suite and performs migration tasks and data integration. The principal goal of SSIS is to resolve issues regarding workflow applications and data integration. SSIS retrieves data from various sources, like various databases, Excel files, text files, etc., and performs data cleansing, filtering, and sorting. After transforming the data, it then loads into several target locations.
Moreover, it incorporates graphical tools to carry out different functions. Today, several organizations and businesses across the globe have adopted SSIS. Microsoft SQL Server Integration Services has a market share of 10.93% and is ranked second in the list of top data integration service providers. Hence, there are a lot of chances for individuals in this domain. Therefore, you can explore more job opportunities.
This article is ideal for individuals who are looking to prepare for an SSIS developer interview. The SSIS interview questions and answers discussed in this article will help you to ace an interview easily and grab a well-paying SSIS developer job role.
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