ServiceNow Frequently Asked SSIS Interview Questions Answers

Perform an incremental load of data

Tasks Required: 2 Execute SQL Tasks, Data Flow Task

Have the 1st Execute SQL Task retrieve a date from a control table of when the target table was last loaded and place that into a variable.
In the Data Flow Task, create a date range on your query using the variable. Then, update the control table using a 2nd Execute SQL Task to specify when the table was
last updated.

What is data flow task in SSIS?

Data flow task is the pumping mechanism that moves data from source to destination. However, in the case of SSIS, you have much more control of what happens from start to finish.  In fact, you have a set of out of the box transformation components that you snap together to clean and manipulate the data while it is in the data pipeline.

Just as the control flow handles the main workflow of the package, the Data Flow handles the transformation of data. Almost anything that manipulates data falls into the Data Flow Category.

What is data Profiling task?

Data profiling is the process of analyzing the source data to better understand what condition the data is in, in terms of cleanliness, patterns, numbers or nulls, and so on. data profiling task usually be used at the beginning of the development cycle to support the design of the destination database schema. Note that this task is not used when you develop the normal recurring ETL packages.

What is the multicast Transformation in SSIS?

The Multicast transform, as the name implies, can send single data input to multiple output paths easily. You may want to use this transformation to send a path to multiple destinations sliced in different ways.  The multicast transformation is similar to the Split Transformation because both send data to multiple outputs. However, you can not specify the conditions for which part of the data will be in which output in the Multicast transformation.

Move and rename the file at the same time

Tasks Required:
File System Task

Set the File System task to rename the file and point to the directory you’d like to move the file to. This enables you to rename and move the file in the same step.

Loop over an array of data in a table & perform a set of tasks for each row
Tasks Required: Execute SQL Task, Foreach Loop

Use an Execute SQL Task to load the array and send the data into an object variable. Loop over the variable in a Foreach Loop by use an ADO Enumerator.

ServiceNow Frequently Asked SSIS Interview Questions Answers

Difference between Merge and Union All?

The Merge transformation can merge data from two paths into a single output.  The Transform is usefull when you wish to break out your Data Flow into a path that handles certain errors and then merge it back into the main Data Flow downstream after the errors have been handled.  it’s also useful if you wish to merge data from two Data Sources.

Note that the data must be sorted before using the Merge Transformation. you can do this by using the sort transformation prior to the merge or by specifying an ORDER By clause in the source connection.  Also, the metadata must be the same for both paths. For example, CustomerID column cannot be a numeric column in one path and a character column in the other path.

The Union All Transformation works much the same way as the Merge Transformation, but it does not require the data to be sorted. It takes the outputs from multiple sources or transforms and combines them into a single result set.

OLE DB Command Transform?

The OLE DB Command Transform is a component designed to execute a SQL Statement for each row in an input stream. This task is analogous to an ADO Command Object being created, prepared, and executed for each row of a result set. The input stream provides that data for parameters that can be set into the SQL Statement that is either an In – line statement or a stored procedure call.

Execute package task?

The Execute Package Task enables you to build SSIS solutions called parent packages that execute other packages called “Child Packages”.  You’ll find this capability an indispensable part of your SSIS development as your packages begin to grow.

Separating packages into discrete functional workflows makes for shorter development and testing cycles and facilitates best development practices. in SSIS, the child package is aware of the parent package parameters and can reach out and access those parameters – level configuration values.  The majority of the configurable properties are in the Package tab of the Executable package Task Editor.

The first option is to provide the location of the child package.  The options here are either File system and SQL Server.  You can deploy SSIS package in the FIle system task as an .dtsx file, or within the msdb database of a SQL Server instance.  if you select file system, you must first create a new connection manager connection to the child package.

If the child package is located in a SQL Server, you’ll need to provide the OLE DB Connection Manager for the SQL Server that holds your packages.  In either case, browse to and then select the child package within the connection to set the package to execute in the task.

What is Manifest file in SSIS?

Manifiest file is the utility which can be used to deploy the package using wizard on file system and SQL Server database.

What is File system deployment?

File system deployment means to save package file on local or network drive. Then you can use SQL Agent job to schedule when the packages will run.

How to back up or retrieve the SSIS packages?

If your package is deployed on SQL Server then you can back up the MSDB database as all the package on SQL server deploys at MSDB.

What is a transaction in SSIS package and how to implement it?

Packages use transactions to bind the database actions that tasks perform into atomic units. and by doing this maintain data integrity.  Al MS IS container types – packages the For loop, For each loop, and Sequence containers, and the task hosts that encapsulate each task can be configured to use transactions. IS provides three options for configuring transactions: Not supported, Supported, and Required.

Require indicates that the container start a transaction, unless one is already started by its parent container. if a transaction already exists, the containter joins the transaction For example, if a package that is not configured to support transactions includes a Sequence container that uses the Required option, the Sequence Container would start its own transaction. If the package were configured to use the Required option, the Sequence containter would join the package transaction.

Supported indicates that the container does not start a transaction, but joins any transaction started by its parent container. For example, if a package with four Executable SQL tasks starts a transaction and all four tasks use the Supported option, the database updates performed by the Execute SQL tasks are rolled back if any taks fails.  if the package does not start a transaction, the four execute SQL tasks are not bound by a transaction, and no database updates except the ones performed by the failed task are rolled back.

Not Supported indicates that the container does not start a transaction or join an existing transaction. A transaction started by a parent container does not affect child containers that have been configured to Not Support transactions. For instance, if a package is configured to start a transaction and a For Loop Container in the package uses the NotSupported option, none of the tasks in the For Loop can roll back if they fail.

Checkpoint?

A checkpoint is the property in SSIS which enables the project to restart from the point of failure. When we set the property to true package create the checkpoint file which stores the information about package execution and use to restart package from the point of failure.  If the package runs successfully, the checkpoint file is deleted, and then re-created the next time the package runs.

Can I run SSIS packages with SQL Server Express or Web or Workgroup editions?

I have looked at the SQL Server 2008 feature comparison matrix and it lists the express/web and workgroup editions as having the SSIS runtime. Does this mean it is possible to develop SSIS packages using the developer edition, and then deploy and run them on a server running one of the lowly SQL Server editions such as SQL Server 2008 Express edition?

You need dtexec to run SSIS packages from command line.

 How can I manually fail a package in Integration Services?

I am running an Execute SQL Task statement in my SSIS package. The Execute SQL Task is running sql and checking that the tables have more than 1000 rows. If they have less than 1000 rows, I want to fail the package.

How do I force a fail inside of a SQL statement?

AFAIK, tasks in SSIS fail on error. So if your Execute SQL Task has a statment like so in it:

declare @count int
select @count = select count(*) from my_table
if @count < 1000
begin
    raiserror(‘Too few rows in my_table’,16,1)
end
else
begin
    — Process your table here
end
You should get the results you want.

No Process Is on the Other End of the Pipe

I receive this error when I try to connect to SQL Server 2005. I have enabled TCP/IP, Named Pipes, and restarted the server but that is not working.

FYI, I’ve just had the same error.

I switched to Windows authentication, disconnected, then tried to login again with SQL authentication. This time I was told my password had expired. I changed the password and it all worked again.

What is the SSIS package and what does it do?

SSIS (SQL Server Integration Services) is an upgrade of DTS (Data Transformation Services), which is a feature of the previous version of SQL Server. SSIS packages can be created in BIDS (Business Intelligence Development Studio). These can be used to merge data from heterogeneous data sources into SQL Server. They can also be used to populate data warehouses, to clean and standardize data, and to automate administrative tasks.

SQL Server Integration Services (SSIS) is a component of Microsoft SQL Server 2005. It replaces Data Transformation Services, which has been a feature of SQL Server since Version 7.0. Unlike DTS, which was included in all versions, SSIS is only available in the “Standard” and “Enterprise” editions.

Integration Services provides a platform to build data integration and workflow applications. The primary use for SSIS is data warehousing as the product features a fast and flexible tool for data extraction, transformation, and loading (ETL).). The tool may also be used to automate maintenance of SQL Server databases, update multidimensional cube data, and perform other functions.

Loop over a list of files & load each one

Tasks Required: Foreach Loop, Data Flow Task

Configure the Foreach Loop to loop over any particular directory of files. The loop should be configured to output
to a given variable. Map the given variable to a connection manager by using expressions.

Difference between Execute TSQL Task and Execute SQL Task

In SSIS there is one tasks Execute TSQL task which is similar to Execute SQL task. Will see what is the difference between two.

Execute TSQL Task:

Pros: Takes less memory, faster perfomance Cons: Output into variable not supported, Only supports ADO.net connection
Execute SQL Task:

Pros: Support output into variables and multiple types of connection, parameterized query possible. Cons: Takes more memory, slower performance compared to TSQL task.

Precedence Constraints?

A task will only execute if the condition that is set by the precedence constraint preceding the task is met.  By using these constraints, it will choose different execution paths depending on the success or failure of other tasks.

Success – Workflow will proceed when the preceding containter executes successfully. Indicated in control flow by a solid green line. Failure – Workflow will proceed when the preceding container’s execution results in a failure. Indicated in control flow by a solid red line. Completion – Workflow will proceed when the preceding container’s execution completes, regardless of success or failure. Indicated in control flow by a solid blue line.
Expression/Constraint with logical AND – workflow will proceed when specified expression and constraints evaluate to true. Indicated in control flow by a solid color line along with a small ‘fx’ icon next to it.  Color of line depends on logical constraint chosen (e.g. success = green, completion = blue).

What is the use of config file in SSIS?

Config file in SSIS is used to provide inputs to connection manager different properties which package use to assign values at runtime dynamically.

Using config file user need to make changes to the config file which package will take automatically at runtime because of using it you don’t need to every time make changes in the packages in case you are deploying package on multiple servers or locations. There are multiple ways in which configuration values can be stored.

XML configuration file: Store the config file as an XML file..
Environment variable Store the config in on of the environment variables.
Registry entry Store the confi in the registry
Parent package variable Store the config as a variable in the package that contains the tasks.
SQL Server Store the config in t a table in SQL Server

Different between Control Flow and Data Flow?

Control flow is for designing the flow of the package. Data flow is for ETL process. Data Flow is the subset of control flow There will be only one control flow while multiple dataflow can exists. Data flow cannot work without a control flow
All process base taks are part of control flow while ETL related tasks are the part of Dataflow which is again a subset of control flow.

What is Conditional Split transformation in SSIS?

This is just like IF condition which checks for the given condition and based on the condition evaluation, the output will be sent to the appropriate OUTPUT path. It has ONE input and MANY outputs. Conditional Split transformation is used to send paths to different outputs based on some conditions. For example, we can organize the transform for the students in a class who have marks greater than 40 to one path and the students who score less than 40 to another path.

How do you eliminate quotes from being uploaded from a flat file to SQL Server?

This can be done using TEXT QUALIFIER property. 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.

Can you explain how to setup a checkpoint file in SSIS?

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.