sessionphase: fix service latency computation in an error case

If we encounter an error during the logical planning, then the end
execution phase is never set. Previously, we would use that unset value
in order to compute the latency of planning and execution and would get
a negative result. This is now fixed.

Release note: None

pkg/sql/sessionphase/session_phase.go

@@ -146,7 +146,16 @@ func (t *Times) GetServiceLatencyNoOverhead() time.Duration {
 		queryReceivedTime = t.times[SessionQueryReceived]
 	}
 	parseLatency := t.times[SessionEndParse].Sub(queryReceivedTime)
-	planAndExecuteLatency := t.times[PlannerEndExecStmt].Sub(t.times[PlannerStartLogicalPlan])
+	// If we encounter an error during the logical planning, the
+	// PlannerEndExecStmt phase will not be set, so we need to use the end of
+	// planning phase in the computation of planAndExecuteLatency.
+	var queryEndExecTime time.Time
+	if t.times[PlannerEndExecStmt].IsZero() {
+		queryEndExecTime = t.times[PlannerEndLogicalPlan]
+	} else {
+		queryEndExecTime = t.times[PlannerEndExecStmt]
+	}
+	planAndExecuteLatency := queryEndExecTime.Sub(t.times[PlannerStartLogicalPlan])
 	return parseLatency + planAndExecuteLatency
 }