Load Data FAQS

1. What is the purpose of the "Load Data" task?
•  The Load Data task reads data from the source system and loads it into a temporary loading table in the staging area. This data is used in the integration phase for further transformation and loading into the final target tables.
2. When is the "Load Data" task executed?
•  The Load Data task is executed during the loading phase of the data integration process. It happens after the creation of the loading table and is necessary for transferring data into the staging area for subsequent transformations.
3. What does the "Load Data" task do with the source data?
•  The task extracts data from the source database using a dynamically generated SELECT query and then loads that data into the temporary loading table in the staging area. It respects any necessary transformations, filters, and joins defined in the mapping.
4. How does the task handle transformations during data loading?
•  The Load Data task uses the ODI methods to dynamically generate SQL expressions that apply mappings, joins, filters, and grouping to the source data before it is loaded into the staging area. This ensures that only the necessary, transformed data is moved.
5. What is the role of the auto commit setting in this task?
•  The auto commit feature ensures that data loaded into the temporary staging tables is automatically committed without requiring manual intervention. Since the data in the loading table is intermediate, it is automatically committed after the load operation is complete.
6. How are the data columns mapped from the source to the loading table?
•  The data columns are dynamically mapped using the getColList method, which retrieves the source columns and their transformations (expressions) and binds them to the corresponding columns in the target loading table (using aliases like CX_COL_NAME).
7. What is the purpose of the getFilter, getJoin, and getFrom methods?
•  These methods are used to dynamically generate parts of the SQL query:
• getFilter: Retrieves any filter conditions applied to the source data.
• getJoin: Retrieves the join conditions for merging multiple tables.
• getFrom: Specifies the source table or query from which data is being extracted. These methods ensure that the correct data is selected from the source database.
8. How is the data inserted into the loading table?
•  After selecting the data from the source, an INSERT INTO statement is generated to insert the selected and transformed data into the loading table in the staging area. The source attributes are dynamically bound to their corresponding columns in the target table.
9. What are bind variables like :[CX_COL_NAME] used for?
•  Bind variables like :[CX_COL_NAME] are placeholders in the INSERT statement that are replaced with the actual source data when the query is executed. These variables ensure that the source data is correctly mapped to the corresponding columns in the target loading table.
10. Can I modify the data loading process?
•  Yes, you can modify the data loading process by adjusting the Knowledge Module or changing the source-to-target mapping in ODI Studio. This can include adding new transformations, applying additional filters, or modifying the SQL queries used for data extraction.