add index on Log.componentName

app/models/log.js

@@ -20,7 +20,7 @@ const LOG_LEVEL_LIST = [
 
 const LogSchema = new Schema({
   created: { type: Date, default: Date.now, required: true, index: -1, expires: '7d' },
-  componentName: { type: String, required: true },
+  componentName: { type: String, required: true, index: 1 },
   level: { type: String, enum: LOG_LEVEL_LIST, required: true, index: true },
   message: { type: String },
   metadata: { type: Schema.Types.Mixed },