Harman Brar

• Jun 5th, 2005

 

SCD 1: Complete overwrite 
SCD 2: Preserve all history. Add row 
SCD 3: Preserve some history. Add additional column for ol/new.

murali

• Jul 28th, 2005

 

SCD Type 1, the attribute value is overwritten with the new value, obliterating the historical attribute values.For example, when the product roll-up 
changes for a given product, the roll-up attribute is merely updated with the current value. 
SCD Type 2,a new record with the new attributes is added to the dimension table. Historical fact table rows continue to reference the old dimension key with the old roll-up attribute; going forward, the fact table rows will reference the new surrogate key with the new roll-up thereby perfectly partitioning history.  
SCDType 3, attributes are added to the dimension table to support two simultaneous roll-ups - perhaps the current product roll-up as well as ?current version minus one?, or current version and original. 

ravi kumar guturi

• Mar 9th, 2006

 

SCD:-------- The value of dimensions is used change very rarely, That is called Slowly Changing dimensions

Here mainly 3

1)SCD1:Replace the old values overwrite by new values

2)SCD2:Just Creating Additional records

3)SCD3:It's maintain just previous and recent

In the SCD2 again 3

1)Versioning

2)Flagvalue

3)Effective Date range

Versioning:Here the updated dimensions inserted in to the target along with version number

The new dimensions will be inserted into the target along with Primary key

Flagvalue:The updated dimensions insert into the target along with 0

and new dimensions inset into the target along with 1

Manesh Mathen

• Nov 9th, 2006

 

SCD1,SCD2 and SCD3 can be also

Type I,Type II,Type III Dimensions:
         Type I
              -Changed attribute overwrites the  existing one.
              eg: If income of customer changes from 4000 to 5000 it will simply replace
                  4000 by 5000.
         Type II Dimension
              - For the changed attribute a new record is created.
              eg: If the income of customer is changed from 4000 to 5000,then a new record
                  is created with income 5000 and the previous one will remain as itis.This
                   will help us to record the history of data.
        Type III Dimension
               -Here a new column will be added to capture the change.
               eg: If the income of customer increases from 4000 to 5000,then a new column will,
                   be added to the existing row titled "new income".So in that record 2 cols
                   will be there "income" and  "new income".

chandrarekha

• May 8th, 2007

 

SCD1, SCD2, SCD3 are also called TYPE1, TYPE2, TYPE3 dimensions

Type1: It never maintains history in the target table. It keeps the most recent updated record in the data base.

Type2: It maintains full history in the target. It maintains history by inserting the new record for each change.

Type3: It keeps the both current and previous values in the target.

snareshinfo

 Profile Answers by snareshinfo 

• Nov 22nd, 2008

 

SCD1: It never maintains history in the target table. It keeps the most
recent updated record only in the data base.

SCD2: It maintains full history in the target. It maintains history by inserting
the new record and updating for each change.

SCD3: It keeps the both current and previous values only in the target.

sharuvijay

 Profile Answers by sharuvijay Questions by sharuvijay

• Jan 28th, 2009

 

SCD1-> Slowly Changing Dimension Type1

This type will overwrite new records with old records without caring about the history.

SCD2-> Slowly Changing Dimension Type2

This type will create a duplicate records with neccessary changes without disturbing the history

SCD3-> Slowly Changing Dimension Type3

This will create a new column which shows the history and current record.

kalyan

• Nov 22nd, 2013

 

The value of dimensions is used change very rarely, That is called Slowly Changing dimensions.

they are 3 types

scd1
scd2
scd3

scd1:it used Replace the old values overwrite by new values
scd2:Creating Additional records
scd3:Its maintain just previous and recent

Ishu

• Feb 20th, 2015

 

SCD1: in SCD1, no history is maintained.
SCD2: whole history is maintained.
SCD3: just the current and last record is stored.