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.

what is informatica metadata?

1037

---

What do mean by local and global repository?

1226

---

How to generate sequence numbers?

1088

---

what is the -ve test case in your project.

2407

---

How to create Target definition for flat files?

1225

---

Whats the difference between informatica powercenter server, repositoryserver and repository?

1174

---

How identifying bottlenecks in various components of informatica and resolving them?

1132

---

What are mapplets?

1271

---

can u any challenge your project?

2033

---

In how many ways we can create ports?

1123

---

What is target designer and target load order?

1104

---

How to partition the Session?

1113

---

Explain the difference between mapping parameter and mapping variable?

1038

---

explain one complex mapping with logic? sales project?

6668

---

What is rank transformation?

991

---