SQL Loader is a powerful utility in Oracle Database that allows you to efficiently load data from external files into database tables. While SQL Loader provides robust error handling mechanisms by default, there are advanced strategies that you can implement to enhance error handling and improve data loading accuracy.
In this blog post, we will discuss some advanced error handling strategies that you can employ when using SQL Loader.
Table of Contents
Introduction
When loading data using SQL Loader, errors can occur due to various reasons such as data format issues, constraint violations, or invalid values. By default, SQL Loader stops loading when it encounters an error and rolls back the entire operation. However, in some scenarios, you may want to handle errors differently to continue loading the rest of the data.
Error Logging
One strategy to handle errors in SQL Loader is to enable error logging. By using the ERRORS parameter with a positive value, you can tell SQL Loader to skip a specified number of error records and continue loading the remaining data. The skipped error records can be logged into a separate error table, allowing you to analyze and fix the issues later.
Here’s an example of enabling error logging in SQL Loader:
sqlldr userid=scott/tiger control=data.ctl errors=10 log=error.log
In the above example, SQL Loader will skip up to 10 error records and log them into the error.log file for further analysis.
Bad File Handling
Another strategy is to specify a bad file name using the BAD parameter. The bad file contains records that are not loaded due to errors encountered during the SQL Loader operation. By assigning a bad file name, you can separate these records from successfully loaded data and easily identify the cause of errors.
Here’s an example of specifying a bad file in SQL Loader:
sqlldr userid=scott/tiger control=data.ctl bad=data.bad
In the above example, SQL Loader will generate a data.bad file containing records that couldn’t be loaded due to errors.
Reject File Handling
The reject file is another option for handling erroneous data in SQL Loader. Unlike the bad file, which contains records that couldn’t be loaded due to errors, the reject file holds records that don’t adhere to specified data format constraints. This allows you to separate data that doesn’t meet your defined criteria, making it easier to review and correct them.
Here’s an example of specifying a reject file in SQL Loader:
sqlldr userid=scott/tiger control=data.ctl discard=data.reject
In the above example, SQL Loader will generate a data.reject file containing records that were discarded due to format violations.
Summary
SQL Loader provides advanced error handling strategies to handle errors encountered during data loading. By using error logging, bad file handling, and reject file handling techniques, you can enhance the error handling capabilities of SQL Loader and ensure the accuracy of your data.
Remember to analyze the error logs, bad files, and reject files generated by SQL Loader to identify and resolve any issues with your data.
#sqlloader #errorhandling