Q.What is surrogate key?
Answer: surrogate key is a system generated sequential number
which acts as a primary key.
Q.Differences Between Ab-Initio and Informatica?
Answer: Informatica and Ab-Initio both support parallelism. But Informatica supports only one type of parallelism but the Ab-Initio supports three types of parallelisms.
Pipe Line parallelism.
We don?t have scheduler in Ab-Initio like Informatica , you need to schedule through script or you need to run manually.
Ab-Initio supports different types of text files means you can read same file with different structures that is not possible in Informatica, and also Ab-Initio is more user friendly than Informatica .
Informatica is an engine based ETL tool, the power this tool is in it?s transformation engine and the code that it generates after development cannot be seen or modified.
Ab-Initio is a code based ETL tool, it generates ksh or bat etc. code, which can be modified to achieve the goals, if any that can not be taken care through the ETL tool itself.
Initial ramp up time with Ab-Initio is quick compare to Informatica, when it comes to standardization and tuning probably both fall into same bucket.
Ab-Initio doesn?t need a dedicated administrator, UNIX or NT admin will suffice, where as Informatica need a dedicated administrator.
With Ab-Initio you can read data with multiple delimiter in a given record, where as Informatica force you to have all the fields be delimited by one standard delimiter
Error Handling ? In Ab-Initio you can attach error and reject files to each transformation and capture and analyze the message and data separately. Informatica has one huge log! Very inefficient when working on a large process, with numerous points of failure.
Q.What is the difference between rollup and scan?
Answer : By using rollup we cant generate cumulative summary records for that we will be using scan
Q.Why we go for Ab-Initio?
Answer : Ab-Initio designed to support largest and most complex business applications.
We can develop applications easily using GDE for Business requirements.
Data Processing is very fast and efficient when compared to other ETL tools.
Available in both Windows NT and UNIX
Q.What is the difference between partitioning with key and round robin?
PARTITION BY KEY:
In this, we have to specify the key based on which the partition will occur. Since it is key based it results in very well balanced data. It is useful for key dependent parallelism.
PARTITION BY ROUND ROBIN:
In this, the records are partitioned in sequential way, distributing data evenly in blocksize chunks across the output partition. It is not key based and results in well balanced data especially with blocksize of 1. It is useful for record independent parallelism.
Q.How to Create Surrogate Key using Ab Initio?
Answer. A key is a field or set of fields that uniquely identifies a record in a file or table.
A natural key is a key that is meaningful in some business or real-world sense. For example, a social security number for a person, or a serial number for a piece of equipment, is a natural key.
A surrogate key is a field that is added to a record, either to replace the natural key or in addition to it, and has no business meaning. Surrogate keys are frequently added to records when populating a data warehouse, to help isolate the records in the warehouse from changes to the natural keys by outside processes.
Q.What are the most commonly used components in a Ab-Initio graphs?
input file / output file
input table / output table
lookup / lookup_local
gather / concatenate
join with db
filter by expression
sort (single or multiple keys)
partition by expression / partition by key