Common Issues and Solutions

1. Connection Refused Errors

Issue: When attempting to connect to the HSQLDB server, you receive a connection refused error.

Solution: Ensure that the HSQLDB server is running and listening on the correct port. Verify the JDBC URL and check for any firewall restrictions.

2. "User Lacks Privilege or Object Not Found" Errors

Issue: Executing a query results in an error indicating that the user lacks privilege or the object is not found.

Solution: Check for case sensitivity in table and column names. HSQLDB treats unquoted identifiers as uppercase. Ensure that the correct schema is being used and that the user has the necessary privileges.

3. Data Truncation Errors

Issue: Inserting data into a table results in a data truncation error.

Solution: Verify that the data being inserted does not exceed the defined column sizes. Adjust the column definitions if necessary to accommodate larger data.

4. "Statement is Not in Batch Mode" Errors

Issue: Executing a batch operation results in an error stating that the statement is not in batch mode.

Solution: Ensure that batch operations are properly initiated and that the JDBC driver supports batch processing. Check for any data size issues that may be causing the error.

5. High CPU Usage

Issue: HSQLDB consumes 100% CPU, leading to performance degradation.

Solution: Investigate client-side or network issues that may be causing excessive load. Enable application logging to identify problematic queries or operations.

Best Practices

• Use consistent naming conventions and be mindful of case sensitivity.
• Regularly back up your databases to prevent data loss.
• Monitor server performance and resource usage.
• Keep HSQLDB updated to benefit from the latest fixes and improvements.

Conclusion

By understanding common issues and implementing best practices, you can effectively troubleshoot and resolve problems encountered when using HSQLDB.