db.collection.unhideIndex()¶

On this page

Definition
Syntax
Behavior
Required Access
Example

Definition¶

db.collection.unhideIndex()¶: mongo Shell Method

This page documents the mongo shell method, and does not refer to the MongoDB Node.js driver (or any other driver) method. For corresponding MongoDB driver API, refer to your specific MongoDB driver documentation instead.

Unhides an existing index from the query planner. Once unhidden, the indexes are immediately available for use.

Syntax¶

db.collection.unhideIndex(<index>)

Parameters¶

The db.collection.unhideIndex() method takes the following parameter:

Parameter Type Description

index

string or document

Specifies the index to unhide from the query planner. You can specify the index either by the index name or by the index specification document.

Tip

You can use the db.collection.getIndexes() method to find the index name or the index specification document.

To unhide a text index, specify the index name.

The db.collection.unhideIndex() is a mongo shell wrapper for the collMod command.

Behavior¶

Index Modifications Reset Statistics¶

Unhiding a hidden index resets its $indexStats.

No-op¶

Unhiding an already unhidden index has no effect on the index. However, the operation will still generate an empty oplog entry.

Required Access¶

If the deployment enforces authentication/authorization, you must have the collMod privilege in the collection’s database.

The built-in role dbAdmin provides the required privileges.

Example¶

The following example unhides an existing index.

First, use db.collection.createIndex() to create a hidden index:

copy

db.restaurants.createIndex( { borough: 1, ratings: 1 }, { hidden: true } );

To verify, run db.collection.getIndexes() on the restaurants collection:

copy

db.restaurants.getIndexes();

The operation returns the following information:

copy

[
   {
      "v" : 2,
      "key" : {
         "_id" : 1
      },
      "name" : "_id_"
   },
   {
      "v" : 2,
      "key" : {
         "borough" : 1,
         "ratings" : 1
      },
      "name" : "borough_1_ratings_1",
      "hidden" : true
   }
]

The index option hidden is only returned if the value is true.

To unhide the index, you can specify either the index key specification document or the index name to the db.collection.unhideIndex() method. The following specifies the index name:

copy

db.restaurants.unhideIndex( "borough_1_ratings_1" );

To verify, run db.collection.getIndexes() on the restaurants collection:

copy

db.restaurants.getIndexes()

The operation returns the following information:

copy

[
   {
      "v" : 2,
      "key" : {
         "_id" : 1
      },
      "name" : "_id_"
   },
   {
      "v" : 2,
      "key" : {
         "borough" : 1,
         "ratings" : 1
      },
      "name" : "borough_1_ratings_1"
   }
]

The index option hidden no longer appears as part of the borough_1_ratings_1 index since the field is only returned if the value is true.