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planCacheClear

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  • Definition
  • Compatibility
  • Syntax
  • Command Fields
  • Required Access
  • Examples
planCacheClear

Removes cached query plans for a collection. Specify a query shape to remove cached query plans for that shape. Omit the query shape to clear all cached query plans.

Tip

In mongosh, this command can also be run through the PlanCache.clear() and PlanCache.clearPlansByQuery() helper methods.

Helper methods are convenient for mongosh users, but they may not return the same level of information as database commands. In cases where the convenience is not needed or the additional return fields are required, use the database command.

This command is available in deployments hosted in the following environments:

  • MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud

Important

This command is not supported in M0, M2, and M5 clusters. For more information, see Unsupported Commands.

The command has the following syntax:

db.runCommand(
{
planCacheClear: <collection>,
query: <query>,
sort: <sort>,
projection: <projection>,
comment: <any>
}
)

The command takes the following optional fields:

Field
Type
Description

query

document

Optional. The query predicate of the query shape. Only the structure of the predicate, including the field names, are significant to the shape; the values in the query predicate are insignificant.

projection

document

Optional. The projection associated with the query shape.

sort

document

Optional. The sort associated with the query shape.

comment

any

Optional. A user-provided comment to attach to this command. Once set, this comment appears alongside records of this command in the following locations:

A comment can be any valid BSON type (string, integer, object, array, etc).

To see the query shapes for which cached query plans exist, see Examples.

On systems running with authorization, a user must have access that includes the planCacheWrite action.

If a collection orders has the following query shape:

{
"query" : { "qty" : { "$gt" : 10 } },
"sort" : { "ord_date" : 1 },
"projection" : { },
"queryHash" : "9AAD95BE"
}

The following operation clears the query plan cached for the shape:

db.runCommand(
{
planCacheClear: "orders",
query: { "qty" : { "$gt" : 10 } },
sort: { "ord_date" : 1 }
}
)

The following example clears all the cached query plans for the orders collection:

db.runCommand(
{
planCacheClear: "orders"
}
)

Tip

See also:

Back

Query Plan Cache