Interview question for Software Engineer in Bengaluru.Explain about SCD type 2 process and different ways of doing it We are splitting the mapping development into six steps. As the name suggests, SCD allows maintaining changes in the Dimension table in the data warehouse. If the End_Date is Null, then it indicates the current row. Record updating date : Record updating timestamp, this will be used for records updated. While mapping the columns, we don’t need any column named OLD_, which is pulled from the Dimension table. Hi,Could you please walk through same thing for IICS? If the End_Date is Null, then it indicates the current row. I can see the image. Just keep only Cust_key, customer_id and location ports in the lookup transformation. You can learn more about this. Create an expression transformation and drag the Cust_Key port of filter transformation (FIL_Changed created in part 3) into the expression transformation. The Mapping Wizard available in the Informatica PowerCenter Designer client provides pre-designed mapping templates to create mappings based on specific requirements like SCD Types 1, 2 & 3. Type 3: The original record is modified to reflect … The new incoming record The fields 'effective date' and 'current indicator' are very often used in … Drag the target definition into the mapping and connect the appropriate ports of update strategy to it. Know more about SCDs at Slowly Changing Dimensions Concepts. SCD Type 1, SCD Type 2, SCD Type 3,Slowly Changing Dimension Types,Advantages & Disadvantages The Slowly Changing Dimension problem is a common one particular to data warehousing.There are in general three ways to solve this type … Type 6 – Hybrid SCD Utilise techniques from SCD Types 1, 2 and 3 to track change; In reality, only types 0, 1 and 2 are widely used, with the others reserved for very specific requirements. The Mapping Wizard available in the Informatica PowerCenter Designer client provides pre-designed mapping templates to create mappings based on specific requirements like SCD Types 1, 2 & 3. Call this expression transformation as "Expr_Date". In the database, create source and dimension tables Click on it to view bigger image. In the expression transformation create a new output port (Begin_Date with date/time data type) and assign value SYSDATE to it. This is the entire … SCD 2 (Complete): Let us drive the point home using a simple scenario. 2(Computer Science and Systems Engineering, Andhra University, India) 3(Computer Science and Systems Engineering, Andhra University, India) Abstract: SCD type 2 will store the entire history in the dimension table. Below image gives the picture of the mapping. The part of the mapping flow is shown in the below image. So at any point of time, the difference between the old values and new values can be retrieved and easily be compared. Slowly Changing Dimension Type 2 also known SCD Type 2 is one of the most commonly used type of Dimension table in a Data Warehouse. In SCD type 2 effective date, the dimension table will have Start_Date and End_Date as the fields. Abstract: SCD type 2 will store the entire history in the dimension table. SCD Type 2 dimension loads are considered to be complex mainly because of the data volume we process and because of the number of transformation we are using in the mapping. Go to the mapping designer tab and create new mapping. Slowly Changing Dimension Type1(SCD-Type1 ) in informatica Slowly Changing Dimensions (SCDs) are dimensions that have data that changes slowly, rather than changing on a time-based, regular schedule For example, you may have a dimension in your database that tracks the sales records of your company's salespeople. --Columns from Dimension (Target) Tables. 31.what are the different types of slowly changing Dimension (SCD) Type 1: The new record replaces the original record. An OUTER Join gives you all the records from the Staging table and the corresponding records from Dimension table. Select the lookup Transformation, enter a name and click on create. In Type 2 Slowly Changing Dimension, if one new record is added to the existing table with a new information then both the original and the new record will be presented having new records with its own primary key. We will be mapping below columns from ‘UPDATE’ group of the Router Transformation to the target table. Go to the properties tab and enter the update strategy expression as DD_INSERT. Go to the properties tab and enter the update strategy expression as DD_UPDATE. Informatica Scd Type-2 implementation What is SCD Type-2: The Type 2 method tracks historical data by creating multiple records for a given natural key in the dimensional tables with separate surrogate keys and/or different version numbers. While mapping the columns, we don’t need any column named OLD_, which is pulled from the Dimension table. CREATE TABLE Students_Dim (Stud_Key Number, Student_Id Number, Student_Name Varchar2(60), Location Varchar2(60)) Follow the steps to generate SCD Type 1 mapping in Informatica. Here is the structure of our Dimension table. Below is the structure of our staging table. These records will then be updated into T_DIM_CUST as a post session SQL. Know more about SCDs at Slowly Changing Dimensions DW Concepts. In Type 2 Slowly Changing Dimension, if one new record is added to the existing table with a new information then, both the original and the new record will be presented having new records with its own primary key. In the Type 2 SCD model the whole history is stored in the database. These are dimensions that gradually change with time, rather than changing on a regular basis. An additional dimension record is created and the segmenting between the old record values and the new (current) value is easy to extract and the history is clear. Alternatively you can generate the SQL query by connecting the database in the Lookup SQL Override expression editor and then add the WHERE clause. The steps involved are: Now create a filter transformation to identify and insert new record in to the dimension table. Here in this article, we will be building an Informatica PowerCenter mapping to load SCD Type 2 Dimension. This is the source. As discussed in the post, using hash values to simulate Change Capture Stage would be a good approach for SCD with Informatica Cloud. As the name suggests, SCD allows maintaining changes in the Dimension table in the data warehouse. Before we go to the mapping design, Lets understand the high level architecture of our Data Warehouse. To identifying new_rec … In this type usually only the current and previous value of dimension is kept in the database. 131,373 views. Confusingly, there is no SCD type 5 in commonly agreed definitions. For eg., in the current month ie.,(01-01-2010) we are provided with an source table with the three columns and three rows in it like (EMpno,Ename,Sal). Now create an update strategy transformation and drag the ports of the expression transformation into it. Call this filter transformation as FIL_Changed. if it is there is no corresponding record in the Dimension table, it returns NULL values for the Dimension table columns. Connect the customer_id port of source qualifier transformation to the In_Customer_Id port of the LKP transformation. The Slowly Changing Dimension transformation in SSIS coordinates the inserting and updating records in data warehouse dimension tables. The part of the mapping flow is shown below. This is used to find the changed records. In this step we will identify the records for INSERT and UPDATE. Now drag the target definition into the mapping and connect the appropriate ports of update strategy transformation to the target definition. Go to the ports tab of expression transformation and create a new output port (End_Date with date/time data type). Now create a filter transformation to identify and insert new record in to the dimension table. The contents in this site is copyrighted to Data Integration Solution and may not be reproduced on other websites. Thanks. There is no difference, you will find the same transformations in IICS as well. Create the source and dimension tables in the database. Go to the properties tab of the LKP transformation and enter the below query in Lookup SQL Override. The example below explains the creation of an SCD Type 2 mapping using the Mapping Wizard.The source table is … so SQ-->LKP(Tgt)-->Router-->Update t/r(Insert)-->Target (For new records/ and old records that come with changes) We are gonna use the SCD-2 style to extract and load the records in to target table. This case is usually ignored by development and business teams but this is an important test which should be done to get the expected time line of the overall process run and completion and also the time taken for pulling the historic data for reporting purposes. To expand the Type 1 Employee Dimension, we use the same Employee data to create a dimension table that captures historical changes in department and position.In this dimension, the change in the rest of the column (such as email address) will be simply updated. Question2: How to Delete duplicate row using Informatica? Create a filter transformation. The SCD Type 1 methodology overwrites old data with new data, and therefore does no need to track historical data . Drag the ports of expression transformation (New_Flag) and source qualifier transformation (Customer_Id, Location) into the filter transformation. Informatica PowerCenter 9 Installation and Configuration Complete Guide, SCD Type 2 Implementation using Informatica PowerCenter, Informatica Performance Tuning Guide, Tuning and Bottleneck Overview - Part 1, Implementing Informatica PowerCenter Session Partitioning Algorithms, Informatica Performance Tuning Guide, Identify Performance Bottlenecks - Part 2. So no other tables other than Dimension table will be involved in the mapping. AS_OF_END_DT : Record will be expired with previous days date. This new port needs to be connected to the customer_id port of the source qualifier transformation. No trace of the old record exists. yes we can do scd type1 and scd type2 in a single mapping itself when the source is same for both. Identifying the changed record and inserting into the dimension table with Begin_Date as the Current date (SYSDATE) and End_Date as NULL. Create a sequence generator and an expression transformation. 250+ Informatica Interview Questions and Answers, Question1: What can we do to improve the performance of Informatica Aggregator Transformation? Map all the ports from the ‘UPDATE’ group of the Router Transformation to target instance T_DIM_CUST. Create an expression transformation with input/output ports as Cust_Key, LKP_Location, Src_Location and output ports as New_Flag, Changed_Flag. Know more about SCDs at Slowly Changing Dimensions Concepts. Hope you guys enjoyed this. Here is the source Top Informatica Interview Questions and Answers 1. Question4: How can we update a record in target table without using Update strategy? Create an expression transformation and drag the Cust_Key port of filter transformation (FIL_Changed created in part 3) into the expression transformation. In our staging table, we have all the columns required for the dimension table attributes. The Type 2 Dimension/Effective Date Range mapping filters source rows based on user-defined comparisons and inserts both new and changed dimensions into the target. SCD type 2 will store the entire history in the dimension table. CUST_ID, AS_OF_END_DT is the Natural key, hence the unique record identifier. SCD Type 2 version implementation - Part 2 In this part, we will identify the new records and insert them into the target with version value as 1. Enter the below expressions for output ports. Select the customer dimension table and click on OK. Edit the lookup transformation, go to the ports tab and remove unnecessary ports. Question3: What are the different lookup cache? Create a new port (IN_Customer_Id) in the lookup transformation. Interview question for Associate in Bhubaneswar.SCD type 2 in Informatica power center designer, how to implement SCD Type 3 – Adding a new column. In Type 2 Slowly Changing Dimension, if one new record is added to the existing table with a new information then, both the original and the new record will be presented having new records with its own primary key. Now we understand the ETL Architecture, Staging Table, Dimension Table and the design considerations, we can go to the mapping development. Go to the filter transformation properties and enter the filter condition as changed_flag =1. In this Type 2, the old values will not be replaced but a new row containing the new values will be added to the product table. OLD_CUST_KEY : To uniquely identify  the Dimension Column. The records which are identified as UPDATE will have to have a new(active) version inserted. SSIS Slowly Changing Dimension Type 2 (SCD 2): If you want to maintain the historical data of a column, then mark them as Historical attributes.If your Dimension table members (or Columns) marked as Historical attributes, then it will maintain the current record, and on top of that, it will create a new record with changing details. Go to the conditions tab of the lookup transformation and enter the condition as Customer_Id = IN_Customer_Id. Now create an update strategy transformation and drag the ports of Filter transformation (customer_id, location) into the update strategy transformation. But with same source we will never face that situation if so the … SCD Type2 Mapping. Now we require using the SCD Type 1 method to load the data present in the source table into the student dimension table. With Type 2, we have unlimited history preservation as a new record is inserted each time a change is made. 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