two types of schemas r there: Star schema and snow flake
Schema: in Snow flake schema normalozation is promoted
where as in star schema denormalization is promoted. incase
of snowflake schema DB size will be saved but no of joins
will be increased and poor performance compare with star
There are 3 types of Schemas,
1)Star Schema-It is defined as the fact table is centrally located,surrounded by dimension tables is called star schema.In that dimension tables are denormalized and fact table is normalized.(or)Star schema is defind as two or more fact and two or more dimension tables that are related to foreigh keys.
2)Snowflake Schema-It is defind as the Denormalized Dimensions tables are can be splited into two or more normalized dimensions is called snowflake schema.In that both dimensions and fact tables are normalized.
3)Hybride Schema-It is defind as a dimension table is shared by two or more fact tables.
There are 3 types of Schemas :
1. Star Schema -The star schema architecture is the
simplest data warehouse schema. It is called a star schema
because the diagram resembles a star, with points radiating
from a center. The center of the star consists of fact
table and the points of the star are the dimension tables.
Usually the fact tables in a star schema are in third
normal form(3NF) whereas dimensional tables are de-
normalized. Despite the fact that the star schema is the
2. Snow Flake Schema - The snowflake schema architecture is
a more complex variation of the star schema used in a data
warehouse, because the tables which describe the dimensions
3. Fact Constallation Schema : For each star schema it is
possible to construct fact constellation schema(for example
by splitting the original star schema into more star
schemes each of them describes facts on another level of
dimension hierarchies). The fact constellation architecture
contains multiple fact tables that share many dimension
There are two types of shemas
1 star schema , 2 snowflake schema
star schema : a fact table related to tha dimension tables
like in the fact table it contain refernce keys of
dimension tables. and dimension tables dont related to the
other parent table . it view like a star so its call star
schema. if this use to avoid more joins
snowflake schema: a dimenion table with related to the it
hirerchi tables. like time dimensin table year dimension
table, month month dimension table, week dimension table
it view like snowflake
if i have one mapping and we already tuned that mapping for performance,everything is fine and loading will take 1 hr,so without doing any change in mapping how could we reduce the loading time from 1hr to 1/2 hr.
I HAVE 10 records in source. I want to store i record in
target 1, second record in target 2, third record in target
3, 4 th record again in target 11, 5th again in target 2,
6th again in target3 etc.... how it is possible?
Hi 2 every one. i dont have real time experience, and please
suggest me for following questions.
a) we get the source data from what type of source systems?
b) In banking domain project what are the FACT & DIMENTION
tables please list out them?
c) please write some colomn names in a table?
Please reply for aboue questions?..... Thanks in advance.