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A query rule fails to run, and the following error is seen in the application server log:
Expression evaluation error in rule '<rule name>' at function 'queryruleexec': Error evaluating function 'queryruleexec' : Unexpected error executing query (type: [<CDT name>], query: [<rule name>], order by: [[]], filters:[null])...Caused by: com.mysql.jdbc.exceptions.MySQLTimeoutException: Statement cancelled due to timeout or client request
The MySQLTimeoutException suggests that the query has reached the ten second query timeout in Appian Cloud. In on-premise environments of Appian, the timeout value may differ based on the configuration.
Review the 'Execute Time (ms)' column of the perf_monitor_rdbms_slow.csv log located in <APPIAN_HOME>/logs/perflogs to confirm if the failed query has exceeded the configured timeout value.
The query timeout value cannot be modified in Appian Cloud. Instead, the query should be optimized so that the data can be returned within ten seconds.
Also see: Database Performance Best Practices and An Introduction to Query Optimization.
This article applies to all versions of Appian.
Last Reviewed: August 2018