How to resolve golden gate blocking sessions

GoldenGate blocking sessions can be a frustrating issue for database administrators. Here’s a simplified guide to help you identify and resolve them:

Table of Contents

What Causes Blocking Sessions?

Long-running transactions: Transactions that take a long time to commit can block other sessions.
Insufficient resources: Lack of system resources (CPU, memory, disk I/O) can slow down processes and cause blocking.
Database design issues: Poorly designed tables or indexes can lead to performance bottlenecks and blocking.
GoldenGate configuration errors: Incorrectly configured parameters or mappings can cause issues.

How to Identify Blocking Sessions

Check GoldenGate logs: Look for error messages related to blocking sessions or replication delays.
Monitor database performance: Use tools like Oracle’s AWR reports to identify performance bottlenecks.
Analyze GoldenGate statistics: Check for unusual wait times or high error rates.

Resolving Blocking Sessions

Identify the root cause: Determine the reason for the blocking using the methods mentioned above.
Kill blocking sessions: If necessary, kill the blocking session using the ALTER SYSTEM KILL SESSION command. However, use this with caution as it can cause data inconsistencies.
Optimize database performance: Tune database parameters, create indexes, or modify SQL statements to improve performance.
Review GoldenGate configuration: Ensure correct mappings, trail file locations, and parameter settings.
Increase resources: If necessary, allocate more CPU, memory, or disk space to the GoldenGate process.
Implement deadlock detection: Use GoldenGate’s deadlock detection features to prevent blocking issues.
Monitor and adjust: Continuously monitor GoldenGate performance and make necessary adjustments.

Remember: Resolving blocking sessions often requires a combination of these steps. It’s essential to analyze the specific situation carefully before taking action.

GoldenGate Commands and Troubleshooting Tips

GoldenGate provides several commands to help you manage and troubleshoot your replication process. Here are some common ones:

Basic Commands

INFO ALL: Shows information about all GoldenGate processes.
INFO EXTRACT/REPLICAT: Displays details about specific processes.
START MANAGER/EXTRACT/REPLICAT: Starts the specified process.
STOP MANAGER/EXTRACT/REPLICAT: Stops the specified process.
EDIT PARAM: Modifies parameters in a configuration file without stopping the process.
ADD EXTRACT/REPLICAT: Adds a new extract or replicat process.
DROP EXTRACT/REPLICAT: Removes an extract or replicat process.

Troubleshooting Techniques

Check log files: GoldenGate generates detailed log files that provide information about errors and warnings.
Monitor performance: Use tools like INFO EXTRACT/REPLICAT DETAIL to check for performance issues.
Analyze lag: Monitor replication lag to identify potential problems.
Review configuration files: Ensure correct parameters and mappings are defined.
Test with a small dataset: Create a test environment to isolate issues.
Use debugging options: Enable debug mode to get more detailed information about errors.
Contact Oracle support: If you’re still facing issues, reach out to Oracle for assistance.

Remember: These are just some basic commands and techniques. GoldenGate offers a wide range of options and features. Always refer to the official documentation for the most accurate and up-to-date information.