# Create One Shard Key Analysis for One Cluster **POST /api/atlas/v2/groups/{groupId}/clusters/{clusterName}/shardKeyAnalyses** Analyzes how well one candidate shard key would distribute one collection across the shards of the specified cluster. This endpoint accepts the request and returns immediately: the `Location` header carries the URI of the operation that tracks the analysis. Poll that operation until its `status` is terminal, then follow its `resultHref` to read the analysis. MongoDB Cloud validates and authorizes the request before accepting it, so a rejected submission returns a `4xx` status and never an operation in a failed state. A namespace that is well formed but absent cannot be detected before the analysis runs and surfaces as a failed operation. ## 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 that contains the collection to analyze. ### 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) Shard key to analyze, and which metrics to compute for it. - **includeKeyCharacteristics** (boolean) Flag that indicates whether to return the cardinality, frequency and monotonicity of the candidate shard key. - **includeReadWriteDistribution** (boolean) Flag that indicates whether to return how reads and writes would be routed across shards under the candidate shard key. This requires query sampling to have collected operations for the namespace. - **namespace** (string) Combination of the database and collection to analyze, written as `.`. - **shardKey** (array[object]) Candidate shard key, given as one object per shard key field in the order the fields form the key. Field order is significant: `[{"a": "1"}, {"b": "1"}]` and `[{"b": "1"}, {"a": "1"}]` are different shard keys. At most one field may be `hashed`. ## Responses ### 202 Accepted #### Headers - **Location** (string(uri)) URI of the operation that tracks this analysis. - **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. ### 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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