Here are some SSIS related Interview Questions with answers.
1. What is the control flow
Answer: In SSIS a workflow is called a control-flow. A control-flow links together our modular data-flows as a series of operations in order to achieve a desired result.
A control flow consists of one or more tasks and containers that execute when the package runs.
To control order or define the conditions for running the next task or container in the package control flow, you use precedence constraints to connect the tasks and containers in a package.
A subset of tasks and containers can also be grouped and run repeatedly as a unit within the package control flow.
SQL Server 2005 Integration Services (SSIS) provides three different types of control flow elements: containers that provide structures in packages, tasks that provide functionality, and precedence constraints that connect the executables, containers, and tasks into an ordered control flow.
2. What is a data flow
Answer: A data flow consists of the sources and destinations that extract and load data, the transformations that modify and extend data, and the paths that link sources, transformations, and destinations.
Before you can add a data flow to a package, the package control flow must include a Data Flow task. The Data Flow task is the executable within the SSIS package that creates, orders, and runs the data flow. A separate instance of the data flow engine is opened for each Data Flow task in a package.
SQL Server 2005 Integration Services (SSIS) provides three different types of data flow components: sources, transformations, and destinations. Sources extract data from data stores such as tables and views in relational databases, files, and Analysis Services databases. Transformations modify, summarize, and clean data. Destinations load data into data stores or create in-memory datasets.
3. How do you do error handling in SSIS
Answer: When a data flow component applies a transformation to column data, extracts data from sources, or loads data into destinations, errors can occur. Errors frequently occur because of unexpected data values.
For example, a data conversion fails because a column contains a string instead of a number, an insertion into a database column fails because the data is a date and the column has a numeric data type, or an expression fails to evaluate because a column value is zero, resulting in a mathematical operation that is not valid.
Errors typically fall into one the following categories:
- Data conversion errors, which occur if a conversion results in loss of significant digits, the loss of insignificant digits, and the truncation of strings. Data conversion errors also occur if the requested conversion is not supported.
- Expression evaluation errors, which occur if expressions that are evaluated at run time perform invalid operations or become syntactically incorrect because of missing or incorrect data values.
- Lookup errors, which occur if a lookup operation fails to locate a match in the lookup table.
Many data flow components support error outputs, which let you control how the component handles row-level errors in both incoming and outgoing data. You specify how the component behaves when truncation or an error occurs by setting options on individual columns in the input or output.
For example, you can specify that the component should fail if customer name data is truncated, but ignore errors on another column that contains less important data.
4. How do you do logging in SSIS
Answer: SSIS includes logging features that write log entries when run-time events occur and can also write custom messages.
Integration Services supports a diverse set of log providers, and gives you the ability to create custom log providers. The Integration Services log providers can write log entries to text files, SQL Server Profiler, SQL Server, Windows Event Log, or XML files.
Logs are associated with packages and are configured at the package level. Each task or container in a package can log information to any package log. The tasks and containers in a package can be enabled for logging even if the package itself is not.
To customize the logging of an event or custom message, Integration Services provides a schema of commonly logged information to include in log entries. The Integration Services log schema defines the information that you can log. You can select elements from the log schema for each log entry.
To enable logging in a package:
- In Business Intelligence Development Studio, open the Integration Services project that contains the package you want.
- On the SSIS menu, click Logging.
- Select a log provider in the Provider type list, and then click Add.
5. How do you deploy SSIS packages
Answer: Integration Services (SSIS) makes it simple to deploy packages to any computer.
There are two steps in the package deployment process:
- The first step is to build the Integration Services project to create a package deployment utility.
- The second step is to copy the deployment folder that was created when you built the Integration Services project to the target computer, and then run the Package Installation Wizard to install the packages.
6. How do you schedule SSIS packages to run on the fly
How do you run stored procedure and get data
A scenario: Want to insert a text file into database table, but during the upload want to change a column called as months – January, Feb, etc to a code, – 1,2,3.. .This code can be read from another database table called months. After the conversion of the data , upload the file. If there are any errors, write to error table. Then for all errors, read errors from database, create a file, and mail it to the supervisor.
How would you accomplish this task in SSIS?
What are variables and what is variable scope ?
Answer: Variables store values that a SSIS package and its containers, tasks, and event handlers can use at run time. The scripts in the Script task and the Script component can also use variables. The precedence constraints that sequence tasks and containers into a workflow can use variables when their constraint definitions include expressions.
Integration Services supports two types of variables: user-defined variables and system variables. User-defined variables are defined by package developers, and system variables are defined by Integration Services. You can create as many user-defined variables as a package requires, but you cannot create additional system variables.
Scope: A variable is created within the scope of a package or within the scope of a container, task, or event handler in the package. Because the package container is at the top of the container hierarchy, variables with package scope function like global variables and can be used by all containers in the package. Similarly, variables defined within the scope of a container such as a For Loop container can be used by all tasks or containers within the For Loop container.
Question 1 – True or False
Using a checkpoint file in SSIS is just like issuing the CHECKPOINT command against the relational engine. It commits all of the data to the database.
Answer: False. SSIS provides a Checkpoint capability which allows a package to restart at the point of failure.
Question 2 – Can you explain the what the Import\Export tool
does and the basic steps in the wizard?
Answer: The Import\Export tool is accessible via BIDS or executing the dtswizard command.
The tool identifies a data source and a destination to move data either within 1 database, between instances or even from a database to a file (or vice versa).
Question 3 – What are the command line tools
to execute SQL Server Integration Services packages?
Answer: DTSEXECUI – When this command line tool is run a user interface is loaded in order to configure each of the applicable parameters to execute an SSIS package.
DTEXEC – This is a pure command line tool where all of the needed switches must be passed into the command for successful execution of the SSIS package.
Question 4 – Can you explain the SQL Server Integration Services functionality
in Management Studio?
Answer: You have the ability to do the following:
Login to the SQL Server Integration Services instance
View the SSIS log
View the packages that are currently running on that instance
Browse the packages stored in MSDB or the file system
Import or export packages
Question 5 – Can you name some of the core SSIS components
in the Business Intelligence Development Studio you work with on a regular basis when building an SSIS package?
Answer: Connection Managers
Question Difficulty = Moderate
Question 1 – True or False: SSIS has a default
means to log all records updated, deleted or inserted on a per table basis.
Answer: False, but a custom solution can be built to meet these needs.
Question 2 – What is a breakpoint in SSIS?
How is it setup? How do you disable it?
Answer: A breakpoint is a stopping point in the code. The breakpoint can give the Developer\DBA an opportunity to review the status of the data, variables and the overall status of the SSIS package.
There are 10 unique conditions exist for each breakpoint.
Breakpoints are setup in BIDS. In BIDS, navigate to the control flow interface. Right click on the object where you want to set the breakpoint and select the ‘Edit Breakpoints…’ option.
Question 3 – Can you name 5 or more of the native
SSIS connection managers?
- OLEDB connection – Used to connect to any data source requiring an OLEDB connection (i.e., SQL Server 2005)
Flat file connection – Used to make a connection to a single file in the File System. Required for reading information from a File System flat file
- ADO.Net connection – Uses the .Net Provider to make a connection to SQL Server 2005 or other connection exposed through managed code (like C#) in a custom task
- Analysis Services connection – Used to make a connection to an Analysis Services database or project. Required for the Analysis Services DDL Task and Analysis Services Processing Task
- File connection – Used to reference a file or folder. The options are to either use or create a file or folder
Question 4 – How do you eliminate quotes
from being uploaded from a flat file to SQL Server?
Answer: In the SSIS package on the Flat File Connection Manager Editor, enter quotes into the Text qualifier field then preview the data to ensure the quotes are not included.
Additional information: How to strip out double quotes from an import file in SQL Server Integration Services
Question 5 – Can you name 5 or more of the main SSIS tool box widgets
and their functionality?
For Loop Container
Foreach Loop Container
ActiveX Script Task
Analysis Services Execute DDL Task
Analysis Services Processing Task
Bulk Insert Task
Data Flow Task
Data Mining Query Task
Execute DTS 2000 Package Task
Execute Package Task
Execute Process Task
Execute SQL Task
Question Difficulty = Difficult
Question 1 – Can you explain one approach to deploy an SSIS package?
Answer: One option is to build a deployment manifest file in BIDS, then copy the directory to the applicable SQL Server then work through the steps of the package installation wizard.
A second option is using the dtutil utility to copy, paste, rename, delete an SSIS Package.
A third option is to login to SQL Server Integration Services via SQL Server Management Studio then navigate to the ‘Stored Packages’ folder then right click on the one of the children folders or an SSIS package to access the ‘Import Packages…’ or ‘Export Packages…’option.
A fourth option in BIDS is to navigate to File | Save Copy of Package and complete the interface.
Question 2 – Can you explain how to setup a checkpoint file in SSIS?
Answer: The following items need to be configured on the properties tab for SSIS package:
CheckpointFileName - Specify the full path to the Checkpoint file that the package uses to save the value of package variables and log completed tasks. Rather than using a hard-coded path as shown above, it’s a good idea to use an expression that concatenates a path defined in a package variable and the package name.
CheckpointUsage – Determines if/how checkpoints are used. Choose from these options: Never (default), IfExists, or Always. Never indicates that you are not using Checkpoints. IfExists is the typical setting and implements the restart at the point of failure behavior. If a Checkpoint file is found it is used to restore package variable values and restart at the point of failure. If a Checkpoint file is not found the package starts execution with the first task. The Always choice raises an error if the Checkpoint file does not exist.
SaveCheckpoints – Choose from these options: True or False (default). You must select True to implement the Checkpoint behavior.
Question 3 – Can you explain different options for dynamic
configurations in SSIS?
Answer: Use an XML file
Use custom variables
Use a database per environment with the variables
Use a centralized database with all variables
Question 4 – How do you upgrade an SSIS Package?
Answer: Depending on the complexity of the package, one or two techniques are typically used:
- Recode the package based on the functionality in SQL Server DTS
- Use the Migrate DTS 2000 Package wizard in BIDS then recode any portion of the package that is not accurate
Here is good link: