informatica faq part2
Q: What are some considerations for determining how many objects and transformations to include in a single mapping?
There are several items to consider when building a mapping. The business requirement is always the first consideration, regardless of the number of objects it takes to fulfill the requirement. The most expensive use of the DTM is passing unnecessary data through the mapping. It is best to use filters as early as possible in the mapping to remove rows of data that are not needed. This is the SQL equivalent of the WHERE clause. Using the filter condition in the Source Qualifier to filter out the rows at the database level is a good way to increase the performance of the mapping.
Log File Organization
Q: Where is the best place to maintain Session Logs?
One often-recommended location is the default "SessLogs" folder in the Informatica directory, keeping all log files in the same directory.
Q: What documentation is available for the error codes that appear within the error log files?
Log file errors and descriptions appear in Appendix C of the PowerCenter TroubleShooting Guide. Error information also appears in the PowerCenter Help File within the PowerCenter client applications. For other database-specific errors, consult your Database User Guide.
Scheduling Techniques
Q: What are the benefits of using workflows with multiple tasks rather than a workflow with a stand-alone session?
Using a workflow to group logical sessions minimizes the number of objects that must be managed to successfully load the warehouse. For example, a hundred individual sessions can be logically grouped into twenty workflows. The Operations group can then work with twenty workflows to load the warehouse, which simplifies the operations tasks associated with loading the targets.
Workflows can be created to run sequentially or concurrently or have tasks in different paths doing either.
• A sequential workflow runs sessions and tasks one at a time, in a linear sequence. Sequential workflows help ensure that dependencies are met as needed. For example, a sequential workflow ensures that session1 runs before session2 when session2 is dependent on the load of session1, and so on. It's also possible to set up conditions to run the next session only if the previous session was successful, or to stop on errors, etc.
• A concurrent workflow groups logical sessions and tasks together, like a sequential workflow, but runs all the tasks at one time. This can reduce the load times into the warehouse, taking advantage of hardware platforms' Symmetric Multi-Processing (SMP) architecture.
Other workflow options, such as nesting worklets within workflows, can further reduce the complexity of loading the warehouse. However, this capability allows for the creation of very complex and flexible workflow streams without the use of a third-party scheduler.
There are several items to consider when building a mapping. The business requirement is always the first consideration, regardless of the number of objects it takes to fulfill the requirement. The most expensive use of the DTM is passing unnecessary data through the mapping. It is best to use filters as early as possible in the mapping to remove rows of data that are not needed. This is the SQL equivalent of the WHERE clause. Using the filter condition in the Source Qualifier to filter out the rows at the database level is a good way to increase the performance of the mapping.
Log File Organization
Q: Where is the best place to maintain Session Logs?
One often-recommended location is the default "SessLogs" folder in the Informatica directory, keeping all log files in the same directory.
Q: What documentation is available for the error codes that appear within the error log files?
Log file errors and descriptions appear in Appendix C of the PowerCenter TroubleShooting Guide. Error information also appears in the PowerCenter Help File within the PowerCenter client applications. For other database-specific errors, consult your Database User Guide.
Scheduling Techniques
Q: What are the benefits of using workflows with multiple tasks rather than a workflow with a stand-alone session?
Using a workflow to group logical sessions minimizes the number of objects that must be managed to successfully load the warehouse. For example, a hundred individual sessions can be logically grouped into twenty workflows. The Operations group can then work with twenty workflows to load the warehouse, which simplifies the operations tasks associated with loading the targets.
Workflows can be created to run sequentially or concurrently or have tasks in different paths doing either.
• A sequential workflow runs sessions and tasks one at a time, in a linear sequence. Sequential workflows help ensure that dependencies are met as needed. For example, a sequential workflow ensures that session1 runs before session2 when session2 is dependent on the load of session1, and so on. It's also possible to set up conditions to run the next session only if the previous session was successful, or to stop on errors, etc.
• A concurrent workflow groups logical sessions and tasks together, like a sequential workflow, but runs all the tasks at one time. This can reduce the load times into the warehouse, taking advantage of hardware platforms' Symmetric Multi-Processing (SMP) architecture.
Other workflow options, such as nesting worklets within workflows, can further reduce the complexity of loading the warehouse. However, this capability allows for the creation of very complex and flexible workflow streams without the use of a third-party scheduler.
posted by dwhfaq | 12:25 AM
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