PlanCache.getPlansByQuery()¶

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Definition¶

PlanCache.getPlansByQuery(<query>, <projection>, <sort>)¶

Displays the cached query plans for the specified query shape.

The query optimizer only caches the plans for those query shapes that can have more than one viable plan.

The method is only available from the plan cache object of a specific collection; i.e.

db.collection.getPlanCache().getPlansByQuery( <query>, <projection>, <sort> )

The PlanCache.getPlansByQuery() method accepts the following parameters:

Parameter	Type	Description
`query`	document	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. Required if specifying the `sort` parameter.
`sort`	document	Optional. The sort associated with the query shape.

返回:	Array of cached query plans for a query shape.

To see the query shapes for which cached query plans exist, use the PlanCache.listQueryShapes() method.

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

If a collection orders has the following query shape:

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

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

db.orders.getPlanCache().getPlansByQuery(
   { "qty" : { "$gt" : 10 } },
   { },
   { "ord_date" : 1 }
)

参见