The ORA-01013: User Process Cancelled error is common in Oracle databases, especially when queries take too long to execute or are interrupted by the user. This error is triggered when a user cancels a long-running operation, or when the operation exceeds time limits.

What is the ORA-01013 Error?

The ORA-01013 error occurs when a SQL query or PL/SQL block is running, but the user cancels it manually, usually because it takes too long or exceeds the specified timeout.

Example:

arduinoCopyORA-01013: user process cancelled

Common Causes of ORA-01013

1. Long-Running Queries

Long queries, especially those that process large datasets, may take too long to execute, leading the user to cancel them.

Solution: Optimize queries using indexes and partitioning to speed them up.

2. Timeout Issues

If a query exceeds the configured timeout limit, it may trigger this error.

Solution: Adjust the timeout settings on the client or database to suit your query execution times.

3. User Intervention

Sometimes users cancel queries due to impatience or system delays.

Solution: Inform users about query times and reduce cancellation possibilities by managing operations better in the application.

4. Resource Exhaustion

If the database is using excessive resources (CPU, memory, I/O), queries may take too long to complete.

Solution: Monitor and optimize resource usage with tools like Oracle Resource Manager and Parallel Execution.

5. Network Issues

Poor network conditions may delay the query response, causing a timeout.

Example

Suppose you run a query to retrieve all records from a huge table without any indexes:

sqlCopySELECT * FROM large_table;

This query might take too long and get canceled by the user due to the ORA-01013 error. You can optimize it by creating an index:

sqlCopyCREATE INDEX idx_large_table ON large_table(column_name);

Now the query will execute faster, reducing the chances of cancellation.

How to Fix ORA-01013

1. SQL Optimization: Use indexes, avoid unnecessary joins, and break queries into smaller pieces.
2. Timeout Management: Adjust timeout settings to allow more time for long-running queries.
3. Resource Management: Use Oracle Resource Manager to control resource consumption.
4. Network Optimization: Ensure the network is stable and TNS settings are configured correctly.

The ORA-01013 error can often be resolved by optimizing queries, managing timeouts, improving resource usage, and addressing network issues. By following these practices, you can minimize the occurrence of this error and ensure better database performance.

Reference