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.

can anybody send me some real time screenshots of mapping in informatica powercenter. i will be vary thankful to him. my e-mail id :- prakashkumar.kumhar@gmail.com

4323

---

what is informatica metadata?

609

---

How can repository reports be accessed without sql or other transformations?

739

---

I have three same source structure tables. But, I want to load into single target table. How do I do this? Explain in detail through mapping flow.

786

---

How to use pmcmd utility command?

595

---

---

What are pre and post-session shell commands?

751

---

What is an Integration service in Informatica?

717

---

What is primary and backup node?

712

---

how many types of dimensions are available in informatica?

570

---

Write the program through which the records can be updated?

526

---

In what scenario we use to improve session performance by pushdown optimization?can any one give example?

5274

---

hi real timers . iam waiting for ur reply regarding ETL TESTING

1818

---

Why union transformation is an active transformation?

665

---

To Provide Support For Mainframes Source Data, which Files Are Used As A Source Definitions?

682

---

Explain sessions and how many types of sessions are there?

594

---