# Create Query Sampling for One Namespace **POST /api/atlas/v2/groups/{groupId}/clusters/{clusterName}/querySampling** Starts query sampling on one namespace of the specified cluster. Sampled queries feed the shard key analysis for the namespace. The response reports the observed sampling state, in which `active` may still be false: the cluster applies the sampling configuration asynchronously. ## Role requirements - Project Data Access Admin - Project Data Access Read Only - Project Data Access Read Write - Project Stream Processing Owner ## Servers - https://cloud.mongodb.com: https://cloud.mongodb.com () ## Authentication methods - Service accounts - Digest auth ## Parameters ### Path parameters - **groupId** (string) Unique 24-hexadecimal digit string that identifies your project. Use the [/groups](#tag/Projects/operation/listProjects) endpoint to retrieve all projects to which the authenticated user has access. **NOTE**: Groups and projects are synonymous terms. Your group id is the same as your project id. For existing groups, your group/project id remains the same. The resource and corresponding endpoints use the term groups. - **clusterName** (string) Human-readable label that identifies the cluster. ### Query parameters - **envelope** (boolean) Flag that indicates whether Application wraps the response in an `envelope` JSON object. Some API clients cannot access the HTTP response headers or status code. To remediate this, set envelope=true in the query. Endpoints that return a list of results use the results object as an envelope. Application adds the status parameter to the response body. - **pretty** (boolean) Flag that indicates whether the response body should be in the prettyprint format. ### Body: application/vnd.atlas.2025-03-12+json (object) Namespace on which to start query sampling. - **namespace** (string) Human-readable label that identifies the namespace (`.`) on which to sample queries. ## Responses ### 201 Created #### Headers - **RateLimit-Limit** () The maximum number of requests that a user can make within a specific time window. - **RateLimit-Remaining** () The number of requests remaining in the current rate limit window before the limit is reached. #### Body: application/vnd.atlas.2025-03-12+json (object) - **active** (boolean) Flag that indicates whether query sampling is observably running on the namespace. May still be `false` in the response to a successful create request; it becomes `true` asynchronously once the cluster applies the sampling configuration. - **namespace** (string) Human-readable label that identifies the namespace (`.`) on which queries are sampled. - **sampledReadsBytes** (integer(int64) | null) Total size in bytes of the read operations sampled on the namespace. - **sampledReadsCount** (integer(int64) | null) Number of read operations sampled on the namespace. - **sampledWritesBytes** (integer(int64) | null) Total size in bytes of the write operations sampled on the namespace. - **sampledWritesCount** (integer(int64) | null) Number of write operations sampled on the namespace. - **samplesPerSecond** (number(double) | null) Maximum number of queries sampled per second on the namespace. MongoDB Cloud sets this rate. - **startTime** (string(date-time) | null) Date and time when query sampling started on the namespace. This parameter expresses its value in the ISO 8601 timestamp format in UTC. ### 400 Bad Request. #### Body: application/json (object) - **badRequestDetail** (object) Bad request detail. - **detail** (string | null) Describes the specific conditions or reasons that cause each type of error. - **error** (integer(int32)) HTTP status code returned with this error. - **errorCode** (string) Application error code returned with this error. - **parameters** (array[object]) Parameters used to give more information about the error. - **reason** (string | null) Application error message returned with this error. ### 401 Unauthorized. #### Body: application/json (object) - **badRequestDetail** (object) Bad request detail. - **detail** (string | null) Describes the specific conditions or reasons that cause each type of error. - **error** (integer(int32)) HTTP status code returned with this error. - **errorCode** (string) Application error code returned with this error. - **parameters** (array[object]) Parameters used to give more information about the error. - **reason** (string | null) Application error message returned with this error. ### 403 Forbidden. #### Body: application/json (object) - **badRequestDetail** (object) Bad request detail. - **detail** (string | null) Describes the specific conditions or reasons that cause each type of error. - **error** (integer(int32)) HTTP status code returned with this error. - **errorCode** (string) Application error code returned with this error. - **parameters** (array[object]) Parameters used to give more information about the error. - **reason** (string | null) Application error message returned with this error. ### 404 Not Found. #### Body: application/json (object) - **badRequestDetail** (object) Bad request detail. - **detail** (string | null) Describes the specific conditions or reasons that cause each type of error. - **error** (integer(int32)) HTTP status code returned with this error. - **errorCode** (string) Application error code returned with this error. - **parameters** (array[object]) Parameters used to give more information about the error. - **reason** (string | null) Application error message returned with this error. ### 409 Conflict. #### Body: application/json (object) - **badRequestDetail** (object) Bad request detail. - **detail** (string | null) Describes the specific conditions or reasons that cause each type of error. - **error** (integer(int32)) HTTP status code returned with this error. - **errorCode** (string) Application error code returned with this error. - **parameters** (array[object]) Parameters used to give more information about the error. - **reason** (string | null) Application error message returned with this error. ### 429 Too Many Requests. #### Headers - **RateLimit-Limit** () The maximum number of requests that a user can make within a specific time window. - **RateLimit-Remaining** () The number of requests remaining in the current rate limit window before the limit is reached. - **Retry-After** () The minimum time you should wait, in seconds, before retrying the API request. This header might be returned for 429 or 503 error responses. #### Body: application/json (object) - **badRequestDetail** (object) Bad request detail. - **detail** (string | null) Describes the specific conditions or reasons that cause each type of error. - **error** (integer(int32)) HTTP status code returned with this error. - **errorCode** (string) Application error code returned with this error. - **parameters** (array[object]) Parameters used to give more information about the error. - **reason** (string | null) Application error message returned with this error. ### 500 Internal Server Error. #### Body: application/json (object) - **badRequestDetail** (object) Bad request detail. - **detail** (string | null) Describes the specific conditions or reasons that cause each type of error. - **error** (integer(int32)) HTTP status code returned with this error. - **errorCode** (string) Application error code returned with this error. - **parameters** (array[object]) Parameters used to give more information about the error. - **reason** (string | null) Application error message returned with this error. 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