DataStage Interview Questions: What is the difference between Sequential file and Hash file? What are the key features of DataStage?
DataStage Interview Questions
What is DataStage?
DataStage is an extract, transform, and load (ETL) tool which is among the most powerful as it comprises the graphical visualizations feature for effective integration of data. It is a combination of tools that function in the design, development, execution, compilation, and management of applications. DataStage is concerned with the extraction, transformation, and loading of data from several sources to the target.
What are the key features of DataStage?
DataStage can process a large amount of data within a short period of time by using a parallel process and partition technique. It can also make connections with several targets from a variety of sources at the same time. The networking within DataStage is at an enterprise level and is used in performing different operations of ETL. It is also a tool based on the graphical user interface (GUI), which allows user interaction with electronic devices.
How can the performance of DataStage jobs be improved?
A vital step in improving the performance of DataStage jobs is the establishment of the models or criteria, followed by the use of different methods for performance testing. During the phase of performance testing, it is important not to include RDBMS. The process of executing DataStage jobs should be done in increments, and the quality of data be evaluated in case it is skewed. If problems are discovered, they are to be resolved in isolation, one at a time. Before understanding and assessing the available tuning knobs, the file systems should be disseminated to eliminate any issues or blockages.
What is NLS in DataStage?
The abbreviation NLS stands for National Language Support. NLS is used to refine data by incorporating other languages such as Spanish, French, German, etc. This may be a requirement for the data to be processed by the data warehouse. The scripts of these languages are similar to those in the English language.
What is the difference between Massive Parallel Processing and Symmetric Multiprocessing?
Massive Parallel Processing is characterized by the exclusive accessing of hardware resources by the processor(s). This means that there is no sharing involved, and this process is referred to as Shared Nothing. Symmetric Multiprocessing is a slower process than Massive Parallel Processing and also differs in that Symmetric Multiprocessing includes the sharing of hardware resources by the processor.
What is the difference between compiling and validating in DataStage?
In compiling a DataStage job, the DataStage engine focuses on the assessment and the verification of the validity of the properties that have been given. In the validating process, the DataStage engine verifies whether all the required properties are in place.
What are the different types of Lookups that exist in DataStage?
Two different types of lookups exist in the DataStage. These are Sparse lkp and Normal lkp. Sparse lkp includes the saving of data directly in the database. This means that it is the fastest of the two. Normal lkp is characterized by data being initially saved in the memory before the lookup is executed.
What is the difference between Sequential file and Hash file?
An obvious feature of hash files is that they save data on a hash key value using a hash algorithm. Sequential files, in contrast, do not have any value wherein data can be saved. The feature of the hash key simplifies and hastens the process of searching in hash files.
How many types of hash files exist in DataStage?
DataStage is composed of two different types of files: Static Hash File and Dynamic Hash File. When the amount of data that is meant to be loaded onto the target database is limited, the system uses the static hash file. The dynamic hash file is used when the amount of data that comes from the source file is unknown.
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