Loading from the fact staging table into the fact table itself is a bit more complex. Disable foreign key constraints before the loads to allow data load in the fact tables while dimension tables are being loaded in parallel.
Identifying new records for the fact table and potentially updates.
How to load fact and dimension tables in informatica. Generally speaking incremental loading for Fact tables is relatively easier as unlike dimension tables here you do not need to perform any look-up on your target table to find out if the source record already exists in the target or not. A Dimension Table is a table in a star schema of a data warehouse. In general fact table loading involves a few common tasks.
Reason is to have the related key value Surrogate Key or the Primary keyForeign Key from the dimension product to the fact sales. Fact table will have sales quantity data aggregated for product for a monthFact table should be incremental for 24 monthsIt should always contain 24 months of data. Preparing your source data to be at the same granularity as your fact table including having the dimension business keys and measures in the source data.
It has two types of columns. The most important thing about loading fact tables is that first you need to load dimension tables and then according to the specification the fact tables. Answered Sep 27 14 at 1433.
Dimension tables are used to describe dimensions. Fact table does not contain a hierarchy whereas the Dimension table contains hierarchies. They contain dimension keys values and attributes.
Data warehouses are built using dimensional data models which consist of fact and dimension tables. Instead of using a numberinteger type field as the surrogate key for your dimension and fact tables model your star schema tables to use a CHARACTER32 as surrogate key field. Acquiring the dimension surrogate keys for any related dimension.
Populate the staging table with all rows that should be in the fact table. Next once you have all dimensions in place you can write a procedure to load fact tables. Either we dont load that record into the fact table or we load it but we put 0 as the.
Normally first we load the dimension table then fact table. If a fact table record does not have a corresponding dimension record basically we have 2 choices. Populate dimension tables with surrogate keys 3.
If you know the way it is handled in informatica then there wont be much difference in writing procedure. In current situation to load dimension and fact in same mapping at same time means We can use constraint based loading in that case and after loading all the dimensions table we can load the data into fact table. 1D_CUSTOMERS SCD 1 2D_PRODUCTS SCD 1 and 3F_SALES_DLY Fact Sales contains daily level data.
The Inferred Dimension Members screen is about handling placeholder records that were added during the fact table load because a dimension member didnt exist when the fact load was run. The SDE mapping takes data from the source table adds the DATASOURCE_NUM_ID and stores it along with the INTEGRATION_ID in the fact staging table. Follow this approach -1.
Create a staging table that looks exactly like your fact table. How to load Dimensions and facts using informatica. Loading data into the fact table at least from the SDE extraction side is very similar to the dimension table.
Fact table helps to store report labels whereas Dimension table contains detailed data. This is the starting point. Also these are dimensions and fact tables.
The fact table is often located in the center of a star schema surrounded by dimension tables. Fact table is defined by their grain or its most atomic level whereas Dimension table should be wordy descriptive complete and quality assured. Swap the staging table and the fact table this usually involves renaming the tables Understand the Consequences of Your Design.
Truncate the staging table. When getting the dimension keys from the dimension table we. Take the Staging tables as source tables and take the dimensions as lookups then load the data into fact table.
METHOD OF LOADING. You can load the dimension table directly but you cannot load the fact table directly You need to look up the dimension table bcoz fact tables contains foreign keys which are the primary keys in dimension table. Those containing facts and other containing foreign keys to dimension tables.
While loading the dimension into the DW we should know this fact that in Star Schema these dimension are not related to each other while in. When loading the data into the fact table you have to get the relavant dimensional keys surrogate keys from all the dimension tables and then insert the records into the fact table. You do a Lookup on each dimension individually.
Load Stage Tables by doing all data standardization and cleansing 2. Inferred members are covered in the DimEmployee dimension ETL later in this Loading a Data Warehouse Topic. If you want to know what product is it then in the fact table you need to have a unique number or identifier for the Product_id which will be used to query in the DIM_Product dimension table to get the details of the product name description quantity Supplier.
When loading facts you use the dimensions natural key to locate the dimensions primary surrogate key.