Logging slow queries

---

Documentation has moved to own html from wiki.

• Current User Guide
• Snapshot User Guide

Leaving old wiki just for reference.

---

SlowQueryListener triggers callback when query execution exceeds specified threshold time.
For example, when 1 min is set to the threshold in a slow query logging listener and a query takes 5 min to run, it will log the query when 1 min has passed while the query is still running.
This is expected behavior; However, elapsed time in ExecutionInfo is not populated because it is still executing the query.

I was asked how to log queries that have passed threshold with elapsed time populated. This behavior can achieved by customizing existing logging query listeners.

Here is sample implementation with SLF4JQueryLoggingListener:

long thresholdInMills = ...
SLF4JQueryLoggingListener listener = new SLF4JQueryLoggingListener() {

    @Override
    public void afterQuery(ExecutionInfo execInfo, List<QueryInfo> queryInfoList) {
  
        // call query logging logic only when it took more than threshold
        if (thresholdInMills <= execInfo.getElapsedTime()) {
            super.afterQuery(execInfo, queryInfoList);
        }

    }
};
listener.setLogLevel(SLF4JLogLevel.WARN);

This implementation will log queries that took longer than specified threshold AFTER query execution has finished. So that, query execution time is populated.