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Percona Server for MongoDB Parameter Tuning Guide

Percona Server for MongoDB includes several parameters that can be changed in one of the following ways:

  • The setParameter variables in the configuration file for persistent changes in production:

    setParameter:
      cursorTimeoutMillis: <int>
      failIndexKeyTooLong: <boolean>
      internalQueryPlannerEnableIndexIntersection: <boolean>
      ttlMonitorEnabled: <boolean>
      ttlMonitorSleepSecs: <int>
    
  • The --setParameter option arguments when running the mongod process for development or testing purposes:

    $ mongod \
      --setParameter cursorTimeoutMillis=<int> \
      --setParameter failIndexKeyTooLong=<boolean> \
      --setParameter internalQueryPlannerEnableIndexIntersection=<boolean> \
      --setParameter ttlMonitorEnabled=<boolean> \
      --setParameter ttlMonitorSleepSecs=<int>
    
  • The setParameter command on the admin database to make changes at runtime:

    > db = db.getSiblingDB('admin')
    > db.runCommand( { setParameter: 1, cursorTimeoutMillis: <int> } )
    > db.runCommand( { setParameter: 1, failIndexKeyTooLong: <boolean> } )
    > db.runCommand( { setParameter: 1, internalQueryPlannerEnableIndexIntersection: <boolean> } )
    > db.runCommand( { setParameter: 1, ttlMonitorEnabled: <int> } )
    > db.runCommand( { setParameter: 1, ttlMonitorSleepSecs: <int> } )
    
variable cursorTimeoutMillis
Value Type:integer
Default:600000 (ten minutes)

Sets the duration of time after which idle query cursors are removed from memory.

variable failIndexKeyTooLong
Value Type:boolean
Default:true

Versions of MongoDB prior to 2.6 would insert and update documents even if an index key was too long. The documents would not be included in the index. Newer versions of MongoDB ignore documents with long index key. By setting this value to false, the old behavior is enabled.

variable internalQueryPlannerEnableIndexIntersection
Value Type:boolean
Default:true

Due to changes introduced in MongoDB 2.6.4, some queries that reference multiple indexed fields, where one field matches no documents, may choose a non-optimal single-index plan. Setting this value to false will enable the old behavior and select the index intersection plan.

variable ttlMonitorEnabled
Value Type:boolean
Default:true

If this option is set to false, the worker thread that monitors TTL Indexes and removes old documents will be disabled.

variable ttlMonitorSleepSecs
Value Type:integer
Default:60 (one minute)

Defines the number of seconds to wait between checking TTL Indexes for old documents and removing them.

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