Final answer:
To avoid duplicate rows of data when re-loading a job, one can use primary keys, check for data existence, utilize ETL tools, apply upsert operations, and maintain a staging area for data processing.
Step-by-step explanation:
When re-loading a job to a database or data warehouse, there are several strategies that can be used to avoid duplicate rows of data. These strategies help to maintain the integrity and quality of data within the system.
- Use of primary keys or unique constraints to ensure that each row is unique and duplicate rows cannot be inserted.
- Checking for existence of the data before insertion by using SQL queries that validate whether a particular set of data already exists.
- Utilizing ETL (Extract, Transform, Load) tools or data integration services that include built-in deduplication capabilities as part of the data transformation process.
- Implementing upsert operations (update and insert) that update existing records if they match on unique identifiers or insert new records if no match is found.
- Maintaining a staging area or temporary space to clean and process data before it's merged into the main database, where duplicate entries can be filtered out.
These strategies should be applied judiciously and in accordance with the specifics of the data being handled as well as the technical capabilities of the database management system in use.