Troubleshooting Apache Cassandra Query Timeout Issue

Problem:

The client experienced timeout errors when running adhoc queries in an Apache Cassandra cluster. Specifically, a query with multiple conditions was timing out due to the coordinator node not receiving responses from replica nodes.

Process:

Here are the steps taken by the expert in the process of resolving the problem:

• Assessment of Query Efficiency: Adhoc queries in Cassandra were explained by the expert as not optimized and were advised against. The inefficiency of querying multiple nodes without proper indexing was highlighted.
• Timeout Adjustment: Acknowledging the client’s need to run adhoc queries, it was suggested by the expert to increase timeout settings in the Cassandra server. Specifically, increasing the range_request_timeout_in_ms and request_timeout_in_ms parameters in the cassandra.yaml file was recommended by tenfold.
• Client Instruction: The client was instructed to adjust the timeout settings in the configuration file and then run the query again using a modified cqlsh command with an increased timeout value.
• Query Modification Guidance: Recognizing the importance of providing all composite keys in the query for efficient data retrieval, the client was advised by the expert to replace the * wildcard with a specific column name or use count(1) instead of count(*) in the query.
• Secondary Index Recommendation: In addition to optimizing the query, the creation of a secondary index on the type column was recommended by the expert to improve query performance.
• Final Follow-up and Troubleshooting Tips: The client was ensured by the expert that the suggested changes had been successfully implemented and troubleshooting tips for future issues, such as monitoring logs for more information, were offered.

Solution:

After a thorough analysis, the following recommendations were made:

1. Increase timeout configurations: range_request_timeout_in_ms and request_timeout_in_ms by 10x.
2. Modify the query to include specific columns and ensure all components of the composite primary key are provided.
3. Create a secondary index on the ‘type’ column for improved query performance.

Conclusion:

By implementing the expert’s recommendations, including modifying the query structure and adjusting timeout configurations, the client successfully resolved the timeout issue in the Apache Cassandra cluster. Ongoing monitoring and communication are advised to address any future issues promptly.