Answer Posted / ramesh

what is junk dimension? Give an example

When developing a dimensional model, we often encounter miscellaneous flags and indicators. These flags do not logically belong to the core dimension tables.

A junk dimension is grouping of low cardinality flags and indicators. This junk dimension helps in avoiding cluttered design of data warehouse. Provides an easy way to access the dimensions from a single point of entry and improves the performance of sql queries.

Example: For example, assume that there are two dimension tables (gender and marital status). The data of these two tables are shown below:

Code:
Table: Gender
Id Gender_status
----------------
1 Male
2 Female

Table: Marital Status
Id Marital_Status
----------------
1 Single
2 Married
Here both the dimensions have low cardinality flags. This will cause maintenance of two tables and decrease performance of sql queries.

We can combine these two dimensions into a single table by cross joining and can maintain a single dimension table. The result of cross join is shown below:

Code:
id gender mrg_status
--------------------
1 Male Single
2 Male Married
3 Female Single
4 Female Married
This new dimension table is called a junk dimension. This will improve the manageability and improves the sql queries performance.

How to go to the older version for a mapping?

608

---

What are the tuning techniques you applied during your last project

1567

---

What is a repository manager?

650

---

How do you remove duplicate records in informatica? And how many ways are there to do it?

719

---

According to his methodology what all you need before you build a datawarehouse

1191

---

---

What is transformation?

666

---

suppose in my source flatfile i have 10000 records in that some of master table records missed table records missed then what will u do

1738

---

How union transformation is used?

596

---

What do you mean by filter transformation?

560

---

What are the advantages of informatica?

576

---

Briefly explain the aggregator transformation?

605

---

How to improve the performance of a session using sorter transformation?

696

---

Explain how to import oracle sequence into informatica?

595

---

What are the steps involved in the migration from older version to newer version of Informatica Server?

1590

---

Describe the scenarios where we go for joiner transformation instead of source qualifier transformation?

622

---