cursor.comment()

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Definition

  • cursor. comment ( )
    • New in version 3.2.

Adds a comment field to the query.

cursor.comment() has the following syntax:

cursor.comment( <string> )

comment() has the following parameter:

ParameterTypeDescription
commentstringThe comment to apply to the query.

Behavior

comment() associates a comment string with the find operation. This can make it easier to track a particular query in the following diagnostic outputs:

See configure log verbosity for the mongod log, the Database Profiler tutorial, or the db.currentOp() command.

Example

The following operation attaches a comment to a query on the restaurants collection:

db.restaurants.find(
   { "borough" : "Manhattan" }
).comment( "Find all Manhattan restaurants" )

Output Examples

system.profile

The following is an excerpt from the system.profile:

{
   "op" : "query",
   "ns" : "guidebook.restaurant",
   "query" : {
      "find" : "restaurant",
      "filter" : {
         "borough" : "Manhattan"
      },
      "comment" : "Find all Manhattan restaurants"
   },
   ...
}

mongod log

The following is an excerpt from the mongod log. It has been formatted for readability.

Important

The verbosity level for QUERY must be greater than 0 . See Configure Log Verbosity Levels

2015-11-23T13:09:16.202-0500 I COMMAND  [conn1]
   command guidebook.restaurant command: find {
      find: "restaurant",
      filter: { "borough" : "Manhattan" },
      comment: "Find all Manhattan restaurants"
   }
   ...

db.currentOp()

Suppose the following operation is currently running on a mongod instance:

db.restaurants.find(
   { "borough" : "Manhattan" }
).comment("Find all Manhattan restaurants")

Running the db.currentOp() command returns the following:

{
   "inprog" : [
      {
         "host" : "198.51.100.1:27017",
         "desc" : "conn3",
         "connectionId" : 3,
         ...

         "op" : "query",
         "ns" : "test.$cmd",
         "command" : {
            "find" : "restaurants",
            "filter" : {
               "borough" : "Manhattan"
            },
            "comment" : "Find all Manhattan restaurants",
            "$db" : "test"
         },
         "numYields" : 0,
         ...
      }
   ],
   "ok" : 1
}