Ab Initio Frequently Asked Questions and Answers

1/02/2010 No Comment

Ab Initio Interview Questions with Answers. 

This page contains Frequently Asked questions on Ab Initio. 

What is ramp limit in ABI?
Answer : When we want to set the reject threshold parameter in component then limit and ramp parameter become available. The two together ie ramp and limit calculate the component tolerance for reject event.Both provides the threshold value of bad records.

limit +(ramp * no. of the records processed)

Explain the difference between dbc and cfg configuration files? 
Answer : Both are database configuration files. cfg is the configuration file for configuring the Database table whereas dbc is the Database configuration file.

What are the compilation errors you came across while executing your graphs?
Answer : If you have not specified DML for any of the component, that will be a compilation error.

What is depth_error ?
Answer : We get depth_error in Ab Initio when two components connected together but does't match their layout.

What is the difference between conventional loading and direct loading ? 
Answer : Utility Mode can be either Direct or Conventional.
In conventional loading, before the data is loaded, all the Table constraints will be checked against the data.
Direct Loading is for faster loading. Here all the constraints will be disabled and data will be loaded directly. Later the data will be checked against the table constraints and the bad data won't be indexed.

Explain the different types of partitions and scenarios in Ab initio.
Answer : The different kind of partitions are broadcast, pbyexpression, pbyroundrobin, pbykey, pwithloadbalance.

How can you see resource usage?
Answer : To check for resource usage. In GDE goto options View > Tracking Details - you will see each component's CPU and memory usage, etc.

What does dependency analysis mean in Ab Initio?
Answer : In Ab Initio, dependency analysis is usually done to find the movement of data, the origin and the destination ie from where it started and where it is flowing.Which graph modified it and what it was modified to. It  is the process by which the EME examines a project on a whole and traces how data is transformed and transferred, field by field, from component to component, within and between different graphs and across projects. It is also something needed to be check if any component is dependent on other and then need to be divided phase by phase.

Consider a scenario during  graph execution, you lost the network connection, do you need  to start the process all over again or will it start from where it stopped?
Answer : It will resume from the point where it stopped.

Can you tell me what does unused port in join component do?

Answer : We need to join the data after appling the join conditions, unused records are send to the unused port and used records send to the output port.

What is a sandbox in Ab Initio? 

Answer : Sandox is a special directory structure which will hold all the files corresponding to the project. In sandbox we store the graph related files, as such it works as a local work area. Its created in local desktop machine. Sandbox also works as a intermediate stage between the GDE and EME.

How did you do version control in Ab Initio? Which tools did you normally use?
Answer : We use EME for version control as well as PVCS. I cases , we may store the graph with out version control.

How do you troubleshoot performance issues in graph?
Answer : To troubleshoot performance, or to increase the performance of the graph use phase & cp, sort components.

Have you worked in production support? What were the different kinds of problems that you encountered while working in a support project?
Answer : Yes, I have worked in a very active production support environment. There are different issue related to visibility of data, system crashes and the like. The most important aspect is to attend the problem on time and constant monitoring.

Explain how can you count the number of records in a multifile system without the use of GDE?

Answer : We can achieve it by the following
M_cat file|wc –l
M_wc dmlof thefile file

What does Scan and Rollup component do and give a scenario where you used them?
Answer : Rollup component give summarize groups of data records & performs aggregate functions like scan generate cumulative totals.

Why you create a stored procedure with the 'with recompile' option?
Answer : The recompile option is very useful when the tables referenced by the stored procedure undergoes a lot of modification, deletion or addition of data. It is because of this heavy modification activity, the execute plan becomes outdated and hence the stored procedure performance goes down. If we create the stored procedure with recompile option, the sql server wont cache a plan for this stored proc and it will be recompiled every time it is run. Hence, you can make it "with recompile" to assure good performance.

Name the different dimension tables that you used and some columns from the fact table?
Answer : Customer, Policy, Claim, Loss and Coverage
Fields from fact table: Loss_mitigation, Cwa_cwp_count, Loss_count, Total_amount

Explain the difference between REDEFINE FORMAT and REFORMAT components?
Answer : REDEFINE FORMAT simply changes the record format on the data as it flows through, thus it leaves the data unchanged. REDEFINE FORMAT copies data records from its input to its output without changing the values in the data records.

The component REFORMAT can actually change the bytes in the data. REFORMAT can change the record format of data records by dropping fields, or by using DML expressions to add up fields, combine the fields, or transform the data within the records.

REDEFINE FORMAT can be used to change or rename fields in a record format without changing the values in the records. Thus, Redefine Format is similar to the DML built-in function reinterpret_as. Typically, REDEFINE FORMAT has different DML on its input and output ports, and hence it enables the unmodified data to be interpreted in a different format.
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