How Is Ssis Runtime Engine Different From The Ssis Dataflow Pipeline Engine?
The SSIS Runtime Engine manages the workflow of the packages during runtime, which means its role is to execute the tasks in a defined sequence. As you know, you can define the sequence using precedence constraints. This engine is also responsible for providing support for event logging, breakpoints in the BIDS designer, package configuration, transactions and connections. The SSIS Runtime engine has been designed to support concurrent/parallel execution of tasks in the package.
The Dataflow Pipeline Engine is responsible for executing the data flow tasks of the package. It creates a dataflow pipeline by allocating in-memory structure for storing data in-transit. This means, the engine pulls data from source, stores it in memory, executes the required transformation in the data stored in memory and finally loads the data to the destination. Like the SSIS runtime engine, the Dataflow pipeline has been designed to do its work in parallel by creating multiple threads and enabling them to run multiple execution trees/units in parallel.
What Is A Task?
A task is very much like a method of any programming language which represents or carries out an individual unit of work. There are broadly two categories of tasks in SSIS, Control Flow tasks and Database Maintenance tasks. All Control Flow tasks are operational in nature except Data Flow tasks. Although there are around 30 control flow tasks which you can use in your package you can also develop your own custom tasks with your choice of .NET programming language.
The SSIS Runtime Engine manages the workflow of the packages during runtime, which means its role is to execute the tasks in a defined sequence. As you know, you can define the sequence using precedence constraints. This engine is also responsible for providing support for event logging, breakpoints in the BIDS designer, package configuration, transactions and connections. The SSIS Runtime engine has been designed to support concurrent/parallel execution of tasks in the package.
The Dataflow Pipeline Engine is responsible for executing the data flow tasks of the package. It creates a dataflow pipeline by allocating in-memory structure for storing data in-transit. This means, the engine pulls data from source, stores it in memory, executes the required transformation in the data stored in memory and finally loads the data to the destination. Like the SSIS runtime engine, the Dataflow pipeline has been designed to do its work in parallel by creating multiple threads and enabling them to run multiple execution trees/units in parallel.
What Is A Task?
A task is very much like a method of any programming language which represents or carries out an individual unit of work. There are broadly two categories of tasks in SSIS, Control Flow tasks and Database Maintenance tasks. All Control Flow tasks are operational in nature except Data Flow tasks. Although there are around 30 control flow tasks which you can use in your package you can also develop your own custom tasks with your choice of .NET programming language.
What Is A Precedence Constraint And What Types Of Precedence Constraint Are There?
SSIS allows you to place as many as tasks you want to be placed in control flow. You can connect all these tasks using connectors called Precedence Constraints. Precedence Constraints allow you to define the logical sequence of tasks in the order they should be executed. You can also specify a condition to be evaluated before the next task in the flow is executed.
These are the types of precedence constraints and the condition could be either a constraint, an expression or both Success (next task will be executed only when the last task completed successfully) or Failure (next task will be executed only when the last task failed) or Complete (next task will be executed no matter the last task was completed or failed).
What Is A Container And How Many Types Of Containers Are There?
A container is a logical grouping of tasks which allows you to manage the scope of the tasks together.
These are the types of containers in SSIS
Sequence Container - Used for grouping logically related tasks together
For Loop Container - Used when you want to have repeating flow in package
For Each Loop Container - Used for enumerating each object in a collection; for example a record set or a list of files.
Apart from the above mentioned containers, there is one more container called the Task Host Container which is not visible from the IDE, but every task is contained in it (the default container for all the tasks).
What Are Variables And What Is Variable Scope?
A variable is used to store values. There are basically two types of variables, System Variable (like ErrorCode, ErrorDescription, PackageName etc) whose values you can use but cannot change and User Variable which you create, assign values and read as needed. A variable can hold a value of the data type you have chosen when you defined the variable.
Variables can have a different scope depending on where it was defined. For example you can have package level variables which are accessible to all the tasks in the package and there could also be container level variables which are accessible only to those tasks that are within the container.
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What Is An Ssis Proxy Account And Why Would You Create It?
When we try to execute an SSIS package from a SQL Server Agent Job it fails with the message "Non-SysAdmins have been denied permission to run DTS Execution job steps without a proxy account". This error message is generated if the account under which SQL Server Agent Service is running and the job owner is not a sysadmin on the instance or the job step is not set to run under a proxy account associated with the SSIS subsystem. Refer to this tip to learn more about it.
Mention How Would You Deploy An Ssis Package On Production?
To deploy SSIS package we need to execute the manifest files and need to determine whether to deploy this into File System or onto SQL Server. Alternatively you can also import package from SSMS from SQL Server or File System.
Explain How To Handle Early Arriving Facts Or Late Arriving Dimension?
Late Arriving Dimension are unavoidable, to handle these we can create a dummy dimensions with natural/business key and keep the rest of the attributes as null or default. So when actual dimension arrives, the dummy dimension is updated with Type 1 change. This is also referred as Inferred Dimensions.
Explain How Can You Do An Incremental Load?
The best and fastest way to do incremental load is by using Timestamp column in the source table and storing the last ETL timestamp.
How Would You Do Logging In Ssis?
Logging Configuration provides an inbuilt feature which can log the detail of various events like onError, onWarning etc to the various options say a flat file, SqlServer table, XML or SQL Profiler.
Mention What Are The Possible Locations To Save Ssis Package?
You can save SSIS package at
SQL Server
Package Store
File System
What Will Be Your First Approach If The Package That Runs Fine In Business Intelligence Development Studio (bids) But Fails When Running From An Sql Agent Job?
The account that runs SQL Agent Jobs might not have the required permission for one of the connections in your package. In such cases, either you can create a proxy account or elevate the account permissions.
Explain What Is The Role Of Event Handlers Tab In Ssis?
On the event handlers tab, workflows can be configured to respond to package events. For instance, you can configure workflow when any task stops, fails or starts.
Explain How You Can Notify The Staff Members About Package Failure?
Either inside the package you could add a Send Mail Task in the event handlers, or you can even set notification in the SQL Agent when the package runs.
How Can An Ssis Package Be Scheduled To Execute At A Defined Time Or At A Defined Interval Per Day?
You can configure a SQL Server Agent Job with a job step type of SQL Server Integration Services Package, the job invokes the dtexec command line utility internally to execute the package. You can run the job (and in turn the SSIS package) on demand or you can create a schedule for a one time need or on a reoccurring basis. Refer to this tip to learn more about it.
How Would You Do Error Handling?
A SSIS package could mainly have two types of errors
a) Procedure Error: Can be handled in Control flow through the precedence control and redirecting the execution flow.
b) Data Error: is handled in DATA FLOW TASK buy redirecting the data flow using Error Output of a component.
How To Pass Property Value At Run Time? How Do You Implement Package Configuration?
A property value like connection string for a Connection Manager can be passed to the pkg using package configurations.Package Configuration provides different options like XML File, Environment Variables, SQL Server Table, Registry Value or Parent package variable.
If You Want To Send Some Data From Access Database To Sql Server Database. What Are Different Component Of Ssis Will You Use?
In the data flow, we will use one OLE DB source, data conversion transformation and one OLE DB destination or SQL server destination. OLE DB source is data source is useful for reading data from Oracle, SQL Server and Access databases. Data Conversion transformation would be needed to remove datatype abnormality since there is difference in datatype between the two databases (Access and SQL Server) mentioned. If our database server is stored on and package is run from same machine, we can use SQL Server destination otherwise we need to use OLE DB destination. The SQL Server destination is the destination that optimizes the SQL Server.
What Is Sql Server Integration Services (ssis)?
SQL Server Integration Services (SSIS) is component of SQL Server 2005 and later versions. SSIS is an enterprise scale ETL (Extraction, Transformation and Load) tool which allows you to develop data integration and workflow solutions. Apart from data integration, SSIS can be used to define workflows to automate updating multi-dimensional cubes and automating maintenance tasks for SQL Server databases.
How Does Ssis Differ From Dts?
SSIS is a successor to DTS (Data Transformation Services) and has been completely re-written from scratch to overcome the limitations of DTS which was available in SQL Server 2000 and earlier versions. A significant improvement is the segregation of the control/work flow from the data flow and the ability to use a buffer/memory oriented architecture for data flows and transformations which improve performance.
What Is The Control Flow?
When you start working with SSIS, you first create a package which is nothing but a collection of tasks or package components. The control flow allows you to order the workflow, so you can ensure tasks/components get executed in the appropriate order.
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