> For the complete MongoDB documentation index, see www.mongodb.com/docs/llms.txt # collMod (database command) ## Definition [`collMod`](https://www.mongodb.com/docs/manual/reference/command/collmod.md#mongodb-dbcommand-dbcmd.collMod) makes it possible to add options to a collection or to modify view definitions. **Tip:** In [`mongosh`](https://www.mongodb.com/docs/mongodb-shell.md#std-program-mongosh), this command can also be run through the [`hideIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.hideindex.md#mongodb-method-db.collection.hideIndex) and [`unhideIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.unhideindex.md#mongodb-method-db.collection.unhideIndex) helper methods. Helper methods are convenient for [`mongosh`](https://www.mongodb.com/docs/mongodb-shell.md#std-program-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. **Note:** The view modified by `collMod` does not refer to materialized views. For discussion of on-demand materialized views, see [`$merge`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/merge.md#mongodb-pipeline-pipe.-merge) instead. ## Compatibility This command is available in deployments hosted in the following environments: - [MongoDB Atlas](https://www.mongodb.com/docs/atlas): The fully managed service for MongoDB deployments in the cloud **Note:** This command is supported in all MongoDB Atlas clusters. For information on Atlas support for all commands, see [Unsupported Commands.](https://www.mongodb.com/docs/atlas/unsupported-commands/) - [MongoDB Enterprise](https://www.mongodb.com/docs/manual/administration/install-enterprise.md#std-label-install-mdb-enterprise): The subscription-based, self-managed version of MongoDB - [MongoDB Community](https://www.mongodb.com/docs/manual/administration/install-community.md#std-label-install-mdb-community-edition): The source-available, free-to-use, and self-managed version of MongoDB ## Syntax The command has the following syntax: ```javascript db.runCommand( { collMod: , : , : , ... } ) ``` For the ``, specify the name of a collection or view in the current database. ## Options ### Change Index Properties To change index options, specify either the key pattern or name of the existing index options you want to change: ```javascript db.runCommand( { collMod: , index: { keyPattern: | name: , expireAfterSeconds: , // Set the TTL expiration threshold hidden: , // Change index visibility in the query planner prepareUnique: , // Reject new duplicate index entries unique: // Convert an index to a unique index }, dryRun: } ) ``` If the index does not exist, the command errors with the message `"cannot find index for ns "`. The `index` option can change the following properties of an **existing** index: | Index Property | Description | | --- | --- | | `expireAfterSeconds` | The number of seconds that determines the expiration threshold of a [TTL Collection.](https://www.mongodb.com/docs/manual/tutorial/expire-data.md#std-label-ttl-collections) If successful, the command returns a document that contains: `expireAfterSeconds_new`, the new value for `expireAfterSeconds`; `expireAfterSeconds_old`, the old value for `expireAfterSeconds`, if the index had a value for `expireAfterSeconds` before. Modifying the index option `expireAfterSeconds` resets the [`$indexStats`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/indexstats.md#mongodb-pipeline-pipe.-indexStats) for the index. If you use TTL indexes created before MongoDB 5.0, or if you want to sync data created in MongDB 5.0 with a pre-5.0 installation, see [Indexes Configured Using NaN](https://www.mongodb.com/docs/manual/tutorial/expire-data.md#std-label-expireData-warning) to avoid misconfiguration issues. The TTL index `expireAfterSeconds` value must be within `0` and `2147483647` inclusive. | | `hidden` | A boolean that determines whether the index is [hidden](https://www.mongodb.com/docs/manual/core/index-hidden.md#std-label-index-type-hidden) or not from the query planner. If the `hidden` value changes, the command returns a document that contains both the old and new values for the changed property: `hidden_old` and `hidden_new`. However, if the `hidden` value has not changed (i.e. hiding an already hidden index or unhiding an already unhidden index), the command omits the `hidden_old` and `hidden_new` fields from the output. To hide an index, you must have [featureCompatibilityVersion](https://www.mongodb.com/docs/manual/reference/command/setfeaturecompatibilityversion.md#std-label-view-fcv) set to `4.4` or greater. Modifying the index option `hidden` resets the [`$indexStats`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/indexstats.md#mongodb-pipeline-pipe.-indexStats) for the index if the value changes. | | `prepareUnique` | A boolean that determines whether the index will accept new duplicate entries. New duplicate entries fail with DuplicateKey errors when `prepareUnique` is `true`. The resulting index can be converted to a unique index. To convert the index, use `collMod` with the `unique` option. If an existing index is updated so that `prepareUnique` is `true`, the index is not checked for pre-existing, duplicate index entries. **New in version 6.0** | | `unique` | A boolean that determines whether the index is unique. A value of `false` is not supported. When `unique` is `true`, `collMod` scans the `keyPattern` index for duplicates and then converts it to a unique index if there are no duplicate index entries. If duplicates are detected during the initial scan, `collMod` returns `CannotConvertIndexToUnique` and a list of conflicting documents. To convert an index with duplicate entries to a unique index, correct any reported conflicts and rerun `collMod`. To end a conversion, set `prepareUnique` to `false`. To see an example of how to convert a non-unique index to a unique index, see [Convert an Existing Index to a Unique Index.](https://www.mongodb.com/docs/manual/core/index-unique/convert-to-unique.md#std-label-index-convert-to-unique) **New in version 6.0** | *Default value:* `false` Only used when `index.unique` is `true`. Before you convert a non-unique index to a unique index, you can run the `collMod` command with `dryRun: true`. If you do, MongoDB checks the collection for duplicate keys and returns any violations. Use `dryRun: true` to confirm that you can convert an index to be unique without any errors. **Note:** If the response containing all conflicting document `_id` values exceeds 8MB, MongoDB returns the following error message instead of listing the specific violations: ```none Cannot convert the index to unique. Too many conflicting documents were detected. Please resolve them and rerun collMod. ``` In this case, resolve duplicate entries until the response is under 8MB, then run `collMod` again to see the remaining violations. ### Validate Documents `validator` allows users to specify [validation rules or expressions](https://www.mongodb.com/docs/manual/core/schema-validation.md#std-label-schema-validation-overview) for a collection. The `validator` option takes a document that specifies the validation rules or expressions. You can specify the expressions using the same operators as the [query operators](https://www.mongodb.com/docs/manual/reference/mql/query-predicates.md#std-label-query-selectors) with the exception of [`$near`](https://www.mongodb.com/docs/manual/reference/operator/query/near.md#mongodb-query-op.-near), [`$nearSphere`](https://www.mongodb.com/docs/manual/reference/operator/query/nearsphere.md#mongodb-query-op.-nearSphere), [`$text`](https://www.mongodb.com/docs/manual/reference/operator/query/text.md#mongodb-query-op.-text), and [`$where`.](https://www.mongodb.com/docs/manual/reference/operator/query/where.md#mongodb-query-op.-where) **Note:** - Validation occurs during updates and inserts. Existing documents do not undergo validation checks until modification. - You cannot specify a validator for collections in the `admin`, `local`, and `config` databases. - You cannot specify a validator for `system.*` collections. The `validationLevel` determines how strictly MongoDB applies the validation rules to existing documents during an update. `"off"` No validation for inserts or updates. `"strict"` **Default** Apply validation rules to all inserts and all updates. `"moderate"` Apply validation rules to inserts and to updates on existing *valid* documents. Do not apply rules to updates on existing *invalid* documents. `"constraint"` Apply validation rules to all inserts and all updates, and guarantee that *every* document in the collection satisfies the rules. **New in version 9.0** To see an example that uses `validationLevel`, see [Specify Validation Level for Existing Documents.](https://www.mongodb.com/docs/manual/core/schema-validation/specify-validation-level.md#std-label-schema-specify-validation-level) **New in version 9.0** A boolean that prepares an existing collection for an upgrade to the `constraint` [`validationLevel`](https://www.mongodb.com/docs/manual/reference/command/collmod.md#mongodb-collflag-validationLevel). Defaults to `false`. To upgrade an existing collection to the `constraint` validation level, first run `collMod` with `prepareConstraintValidationLevel` set to `true`. When `true`, MongoDB blocks [bypassDocumentValidation](https://www.mongodb.com/docs/manual/core/schema-validation/bypass-document-validation.md#std-label-schema-bypass-document-validation) and prevents changes to the [`validator`.](https://www.mongodb.com/docs/manual/reference/command/collmod.md#mongodb-collflag-validator) To see an example that uses `prepareConstraintValidationLevel`, see [Specify constraint Validation.](https://www.mongodb.com/docs/manual/core/schema-validation/specify-validation-level.md#std-label-upgrade-to-constraint-validation) The `validationAction` option determines whether to `error` on invalid documents or just `warn` about the violations but allow invalid documents. **Important:** Validation of documents only applies to those documents as determined by the `validationLevel`. To see an example that uses `validationAction`, see [Choose How to Handle Invalid Documents.](https://www.mongodb.com/docs/manual/core/schema-validation/handle-invalid-documents.md#std-label-schema-validation-handle-invalid-docs) ### Modify Views **Note:** The view modified by this command does not refer to materialized views. For discussion of on-demand materialized views, see [`$merge`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/merge.md#mongodb-pipeline-pipe.-merge) instead. The underlying source collection or [view](https://www.mongodb.com/docs/manual/core/views.md#std-label-views-landing-page). The view definition is determined by applying the specified [`pipeline`](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-pipeline) to this source. Required if modifying a view on a MongoDB deployment that is running with access control. The [aggregation pipeline](https://www.mongodb.com/docs/manual/core/aggregation-pipeline.md#std-label-aggregation-pipeline) that defines the [view.](https://www.mongodb.com/docs/manual/core/views.md#std-label-views-landing-page) **Note:** A view definition `pipeline` cannot include the [`$out`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/out.md#mongodb-pipeline-pipe.-out) or the [`$merge`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/merge.md#mongodb-pipeline-pipe.-merge) stage. This restriction also applies to embedded pipelines, such as pipelines used in [`$lookup`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/lookup.md#mongodb-pipeline-pipe.-lookup) or [`$facet`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/facet.md#mongodb-pipeline-pipe.-facet) stages. Required if modifying a view on a MongoDB deployment that is running with access control. The view definition is public; i.e. [`db.getCollectionInfos()`](https://www.mongodb.com/docs/manual/reference/method/db.getcollectioninfos.md#mongodb-method-db.getCollectionInfos) and `explain` operations on the view will include the pipeline that defines the view. As such, avoid referring directly to sensitive fields and values in view definitions. ```javascript db.runCommand( { collMod: "myView", viewOn: "activities", pipeline: [ { $match: { status: "Q" } }, { $project: { user: 1, date: 1, description: 1} } ] } ) ``` ### Modify Time Series Collections **Note:** If you specify a modification in the `timeseries` parameter of your `collMod` operation, you cannot use other modification options in the same command. You must perform time series modifications in a dedicated command that is separate from other collection modifications. **Note:** This is distinct from using the [`index`](https://www.mongodb.com/docs/manual/reference/command/collmod.md#mongodb-collflag-index) option with the `expireAfterSeconds` property to change the expiration time for a [TTL Collection.](https://www.mongodb.com/docs/manual/tutorial/expire-data.md#std-label-ttl-collections) To enable automatic document removal or modify the current expiration interval for a [time series collection](https://www.mongodb.com/docs/manual/core/timeseries-collections.md#std-label-manual-timeseries-collection), change the `expireAfterSeconds` value: ```javascript db.runCommand( { collMod: , expireAfterSeconds: | "off" } ) ``` Set `expireAfterSeconds` to `"off"` to disable automatic removal, or a non-negative decimal number (`>=0`) to specify the number of seconds after which documents expire. **See also:** [Set up Automatic Removal for Time Series Collections (TTL)](https://www.mongodb.com/docs/manual/core/timeseries/timeseries-automatic-removal.md#std-label-manual-timeseries-automatic-removal) To modify the [granularity](https://www.mongodb.com/docs/manual/core/timeseries/timeseries-granularity.md#std-label-timeseries-granularity) of a time series collection, you can increase `timeseries.granularity` from a shorter unit of time to a longer one: ```javascript db.runCommand( { collMod: "weather24h", timeseries: { granularity: "seconds" | "minutes" | "hours" } } ) ``` To update the custom bucketing fields `bucketRoundingSeconds` and `bucketMaxSpanSeconds` instead of `granularity`, include both custom fields in the `collMod` command and set them to the same value: ```javascript db.runCommand( { collMod: "weather24h", timeseries: { bucketRoundingSeconds: 86400, bucketMaxSpanSeconds: 86400 } } ) ``` You cannot decrease the granularity interval or the custom bucketing values. **Important:** You cannot downgrade below MongoDB 6.3 if any time series collections explicitly specify the custom bucketing fields `bucketMaxSpanSeconds` and `bucketRoundingSeconds`. If possible, convert to the corresponding `granularity`. If you cannot, you must drop the collection before downgrading. To convert a collection from custom bucketing to a `granularity`, value, both `bucketMaxSpanSeconds` and `bucketRoundingSeconds` must be less than or equal to the `granularity` equivalent: | `granularity` | `bucketRoundingSeconds` limit (inclusive) | `bucketMaxSpanSeconds` limit (inclusive) | | --- | --- | --- | | `seconds` | 60 | 3600 | | `minutes` | 3600 | 86400 | | `hours` | 86400 | 2592000 | **See also:** [Set Granularity for Time Series Data](https://www.mongodb.com/docs/manual/core/timeseries/timeseries-granularity.md#std-label-timeseries-granularity) ### Resize a Capped Collection **New in version 6.0** Starting in MongoDB 6.0, you can resize a capped collection. To change a [capped collection's](https://www.mongodb.com/docs/manual/core/capped-collections.md#std-label-manual-capped-collection) maximum size in bytes, use the `cappedSize` option. To change the maximum number of documents in an existing capped collection, use the `cappedMax` option. **Note:** You can't use these commands to resize the oplog. Use [`replSetResizeOplog`](https://www.mongodb.com/docs/manual/reference/command/replsetresizeoplog.md#mongodb-dbcommand-dbcmd.replSetResizeOplog) instead. Specifies a new maximum size, in bytes, for a capped collection. `cappedSize` must be greater than `0` and less than `1e+15` (1 PB). Specifies a new maximum number of documents in a capped collection. Setting `cappedMax` less than or equal to `0` implies no limit. For example, the following command sets the maximum size of a capped collection to 100000 bytes and sets the maximum number of documents in the collection to 500: ```javascript db.runCommand( { collMod: , cappedSize: 100000, cappedMax: 500 } ) ``` ### Change Streams with Document Pre- and Post-Images **New in version 6.0** Starting in MongoDB 6.0, you can use [change stream events](https://www.mongodb.com/docs/manual/reference/change-events.md#std-label-change-stream-output) to output the version of a document before and after changes (the document pre- and post-images): - The pre-image is the document before it was replaced, updated, or deleted. There is no pre-image for an inserted document. - The post-image is the document after it was inserted, replaced, or updated. There is no post-image for a deleted document. - Enable `changeStreamPreAndPostImages` for a collection using [`db.createCollection()`](https://www.mongodb.com/docs/manual/reference/method/db.createcollection.md#mongodb-method-db.createCollection), [`create`](https://www.mongodb.com/docs/manual/reference/command/create.md#mongodb-dbcommand-dbcmd.create), or [`collMod`](https://www.mongodb.com/docs/manual/reference/command/collmod.md#mongodb-dbcommand-dbcmd.collMod). For example, when using the `collMod` command: ```javascript db.runCommand( { collMod: , changeStreamPreAndPostImages: { enabled: true } } ) ``` To check the current `changeStreamPreAndPostImages` setting for a collection, run [`db.getCollectionInfos()`:](https://www.mongodb.com/docs/manual/reference/method/db.getcollectioninfos.md#mongodb-method-db.getCollectionInfos) ```javascript db.getCollectionInfos( { name: "" } )[0].options.changeStreamPreAndPostImages ``` **Output:** ```javascript { changeStreamPreAndPostImages: { enabled: true } } ``` To use `collMod` to enable change stream pre- and post-images for a collection, use the `changeStreamPreAndPostImages` field: ```javascript db.runCommand( { collMod: , changeStreamPreAndPostImages: { enabled: } } ) ``` To enable change stream pre- and post-images for a collection, set `changeStreamPreAndPostImages` to `true`. For example: ```javascript db.runCommand( { collMod: "orders", changeStreamPreAndPostImages: { enabled: true } } ) ``` To disable change stream pre- and post-images for a collection, set `changeStreamPreAndPostImages` to `false`. For example: ```javascript db.runCommand( { collMod: "orders", changeStreamPreAndPostImages: { enabled: false } } ) ``` Pre- and post-images are not available for a [change stream event](https://www.mongodb.com/docs/manual/reference/change-events.md#std-label-change-stream-output) if the images were: - Not enabled on the collection at the time of a document update or delete operation. - Removed after the pre- and post-image retention time set in `expireAfterSeconds`. - The following example sets `expireAfterSeconds` to `100` seconds on an entire cluster: ```javascript use admin db.runCommand( { setClusterParameter: { changeStreamOptions: { preAndPostImages: { expireAfterSeconds: 100 } } } } ) ``` **Note:** The [`setClusterParameter`](https://www.mongodb.com/docs/manual/reference/command/setclusterparameter.md#mongodb-dbcommand-dbcmd.setClusterParameter) command is not supported in MongoDB Atlas clusters. For information on Atlas support for all commands, see [Unsupported Commands in Atlas Clusters.](https://www.mongodb.com/docs/atlas/unsupported-commands.md#std-label-unsupported-commands) - The following example returns the current `changeStreamOptions` settings, including `expireAfterSeconds`: ```javascript db.adminCommand( { getClusterParameter: "changeStreamOptions" } ) ``` - Setting `expireAfterSeconds` to `off` uses the default retention policy: pre- and post-images are retained until the corresponding change stream events are removed from the [oplog.](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-oplog) - If a change stream event is removed from the oplog, then the corresponding pre- and post-images are also deleted regardless of the `expireAfterSeconds` pre- and post-image retention time. Additional considerations: - Enabling pre- and post-images consumes storage space and adds processing time. Only enable pre- and post-images if you need them. - Limit the change stream event size to less than 16 mebibytes. To limit the event size, you can: - Limit the document size to 8 megabytes. You can request pre- and post-images simultaneously in the [change stream output](https://www.mongodb.com/docs/manual/reference/change-events.md#std-label-change-stream-output) if other change stream event fields like `updateDescription` are not large. - Request only post-images in the change stream output for documents up to 16 mebibytes if other change stream event fields like `updateDescription` are not large. - Request only pre-images in the change stream output for documents up to 16 mebibytes if: - document updates affect only a small fraction of the document structure or content, *and* - do not cause a `replace` change event. A `replace` event always includes the post-image. - To request a pre-image, you set `fullDocumentBeforeChange` to `required` or `whenAvailable` in [`db.collection.watch()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.watch.md#mongodb-method-db.collection.watch). To request a post-image, you set `fullDocument` using the same method. - Pre-images are written to the [`config.system.preimages`](https://www.mongodb.com/docs/manual/reference/system-collections.md#mongodb-data-config.system.preimages) collection. - The `config.system.preimages` collection may become large. To limit the collection size, you can set `expireAfterSeconds` time for the pre-images as shown earlier. - To monitor the size of `config.system.preimages`, connect to a shard node on a sharded cluster or a [`mongod`](https://www.mongodb.com/docs/manual/reference/program/mongod.md#mongodb-binary-bin.mongod) node on a replica set. Then, run the following commands: ```javascript use config db.system.preimages.totalSize() db.system.preimages.stats() ``` **Note:** You must have the [`collStats`](https://www.mongodb.com/docs/manual/reference/privilege-actions.md#mongodb-authaction-collStats) privilege action on the `config.system.preimages` collection to run these commands. To run these commands on an MongoDB Atlas deployment, you must have the [`atlasAdmin`](https://www.mongodb.com/docs/manual/reference/built-in-roles.md#mongodb-atlasrole-atlasAdmin) role. - Pre-images are removed asynchronously by a background process. **Important: Backward-Incompatible Feature** Starting in MongoDB 6.0, if you are using document pre- and post-images for [change streams](https://www.mongodb.com/docs/manual/reference/change-events.md#std-label-change-stream-output), you must disable [changeStreamPreAndPostImages](https://www.mongodb.com/docs/manual/reference/command/collmod.md#std-label-collMod-change-stream-pre-and-post-images) for each collection using the [`collMod`](https://www.mongodb.com/docs/manual/reference/command/collmod.md#mongodb-dbcommand-dbcmd.collMod) command before you can downgrade to an earlier MongoDB version. **See also:** - For change stream events and output, see [Change Stream Events.](https://www.mongodb.com/docs/manual/reference/change-events.md#std-label-change-stream-output) - To watch a collection for changes, see [`db.collection.watch()`.](https://www.mongodb.com/docs/manual/reference/method/db.collection.watch.md#mongodb-method-db.collection.watch) - For complete examples with the change stream output, see [Change Streams with Document Pre- and Post-Images.](https://www.mongodb.com/docs/manual/reference/method/db.collection.watch.md#std-label-db.collection.watch-change-streams-pre-and-post-images-example) ### Attach Comment Optional. You can attach a comment to this command. The comment must be a top-level field and can be any valid [BSON type](https://www.mongodb.com/docs/manual/reference/bson-types.md#std-label-bson-types). The comment that you specify appears alongside records of this command in the following locations: - [mongod log messages](https://www.mongodb.com/docs/manual/reference/log-messages.md#std-label-log-messages-ref), in the `attr.command.cursor.comment` field. - [Database profiler](https://www.mongodb.com/docs/manual/reference/database-profiler.md#std-label-profiler) output, in the [`command.comment`](https://www.mongodb.com/docs/manual/reference/database-profiler.md#mongodb-data-system.profile.command) field. - [`currentOp`](https://www.mongodb.com/docs/manual/reference/command/currentop.md#mongodb-dbcommand-dbcmd.currentOp) output, in the [`command.comment`](https://www.mongodb.com/docs/manual/reference/command/currentop.md#mongodb-data-currentOp.command) field. ### Write Concern Optional. A document expressing the [write concern](https://www.mongodb.com/docs/manual/reference/write-concern.md#std-label-write-concern) of the `collMod` command. Omit to use the default write concern. ## Access Control If the deployment enforces authentication/authorization, you must have the following privilege to run the `collMod` command: | Task | Required Privileges | | --- | --- | | Modify a non-capped collection | [`collMod`](https://www.mongodb.com/docs/manual/reference/privilege-actions.md#mongodb-authaction-collMod) in the database | | Modify a view | [`collMod`](https://www.mongodb.com/docs/manual/reference/privilege-actions.md#mongodb-authaction-collMod) in the database and either: no [`find`](https://www.mongodb.com/docs/manual/reference/privilege-actions.md#mongodb-authaction-find) on the view to modify, **or**; both [`find`](https://www.mongodb.com/docs/manual/reference/privilege-actions.md#mongodb-authaction-find) on the view to modify and [`find`](https://www.mongodb.com/docs/manual/reference/privilege-actions.md#mongodb-authaction-find) on the source collection/view. | The built-in role [`dbAdmin`](https://www.mongodb.com/docs/manual/reference/built-in-roles.md#mongodb-authrole-dbAdmin) provides the required privileges. ## Behavior ### Resource Locking The [`collMod`](https://www.mongodb.com/docs/manual/reference/command/collmod.md#mongodb-dbcommand-dbcmd.collMod) command obtains a collection lock on the specified collection for the duration of the operation. ## Examples ### Change Expiration Value for Indexes The following example updates the `expireAfterSeconds` property of an existing TTL index `{ lastAccess: 1 }` on a collection named `user_log`. The current `expireAfterSeconds` property for the index is set to `1800` seconds (or 30 minutes) and the example changes the value to `3600` seconds (or 60 minutes). ```javascript db.runCommand({ collMod: "user_log", index: { keyPattern: { lastAccess: 1 }, expireAfterSeconds: 3600 } }) ``` If successful, the operation returns a document that includes both the old and new value for the changed property: ```javascript { "expireAfterSeconds_old" : 1800, "expireAfterSeconds_new" : 3600, "ok" : 1 } ``` ### Hide an Index from the Query Planner **Note:** To hide an index, you must have [featureCompatibilityVersion](https://www.mongodb.com/docs/manual/reference/command/setfeaturecompatibilityversion.md#std-label-view-fcv) set to `7.0` or greater. The following example [hides](https://www.mongodb.com/docs/manual/core/index-hidden.md#std-label-index-type-hidden) an existing index on the `orders` collection. Specifically, the operation hides the index with the specification `{ shippedDate: 1 }` from the query planner. ```javascript db.runCommand( { collMod: "orders", index: { keyPattern: { shippedDate: 1 }, hidden: true } } ) ``` If successful, the operation returns a document that includes both the old and new value for the changed property: ```javascript { "hidden_old" : false, "hidden_new" : true, "ok" : 1 } ``` **Note:** If the operation is successful but the `hidden` value has not changed (specifically, hiding an already hidden index or unhiding an already unhidden index), the command omits the `hidden_old` and `hidden_new` fields from the output. To hide a text index, you must specify the index by `name` and not by `keyPattern`. **See also:** - [Hidden Indexes](https://www.mongodb.com/docs/manual/core/index-hidden.md#std-label-index-type-hidden) - [`db.collection.hideIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.hideindex.md#mongodb-method-db.collection.hideIndex) - [`db.collection.unhideIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.unhideindex.md#mongodb-method-db.collection.unhideIndex)