TOP Ab Initio Interview Questions and Answers
Explain the difference between the truncate and delete commands?
It is a DDL command, used to delete tables or clusters. Since it is a DDL command hence it is auto commit and Rollback can’t be performed. It is faster than delete.
It is DML command, generally used to delete a record, clusters or tables. Rollback command can be performed , in order to retrieve the earlier deleted things. To make deleted things permanently, “commit” command should be used.
What does dependency analysis mean in Ab Initio?
Dependency analysis will answer the questions regarding datalinage. That is where does the data come from,what applications produce and depend on this data etc.
We can retrieve the maximum (surrogate key) from the existing data,the by using scan or next_in_sequence/reformat we can generate further sequence for new records.
What is the difference between rollup and scan?
By using rollup we cant generate cumulative summary records for that we will be using scan.
How can i run the 2 GUI merge files?
Do you mean by merging Gui map files in WR.If so, by merging GUI map files in GUI map editor it wont create corresponding test script.without test script you cant run a file.So it is impossible to run a file by merging 2 GUI map files.
What methods exist for performance tuning?
The best way would be to perform join at the database, the classical way is when we have two tables that we can bring together by making placing a join component between them. Alternately we can write a query to make the join at the level of a database. The advantage is that only one hit is sent to the database instead of two (the classical method). This makes a real difference in improving performance.
What means writing of wrapper?
Writing of a wrapper will help us run sequential running of two graphs, for instance in order to do this the user must use that feed that was generated by the first graph into the next graph, and for multiple use into the next graph and so on.
What is the reason for using parameterized graphs?
Their role is seen when we are trying to use the same graph many times for various files, in this way we must set parameters for the graph, which get replaced anyway during run. So we can keep one graph version for different files and not different versions.
What is API mode versus the utility mode?
Both API and utility modes are used as connection interfaces to the databases for the purpose of performing specific tasks required by the user. They allows us to easily access different functions that the vendor put for use. The role of each function is related to the nature of the databases. The difference between the two modes is that API is known to be slower but offers a higher range of flexibility than the utility mode. Also API is considered to be a more diagnostic feature.
What is the reason for a database to contain stored procedures?
The main reason is network traffic reduction. Because stored procedures are precompiled SQL blocks, the time of execution can be reduced. In this way the application performance is higher, being stored in the database the procedure will be called by the application and execute faster than in the case is not already compiled. They also provide reusability for different other applications.