> ## Documentation Index > Fetch the complete documentation index at: https://docs.basaltic.sh/llms.txt > Use this file to discover all available pages before exploring further. # List an engine's tunable parameters > The allowlist of settings a parameter group for this engine may carry, with each one's value grammar, bounds, and whether applying it needs a restart. Parameter groups validate against this same catalog, so without it the only way to learn what is tunable is to submit a group and read the 400. Settings the platform owns are absent and are refused. Static platform metadata, not account-scoped. ## OpenAPI ````yaml /api-reference/specs/database.yaml get /v1/engines/{engine_type}/parameters openapi: 3.0.3 info: title: Basaltic Database API version: 1.0.0 description: | Managed database clusters — provision an engine, convert a single node to high availability, fail over between members and restore from a backup. contact: name: Basaltic Support email: ping@basaltic.sh license: name: Proprietary url: https://basaltic.sh/terms servers: - url: https://database.{region}.basaltic.sh description: Regional API endpoint variables: region: default: sa-saopaulo-1 description: Region code security: - SignatureAuth: [] paths: /v1/engines/{engine_type}/parameters: get: tags: - Database summary: List an engine's tunable parameters description: > The allowlist of settings a parameter group for this engine may carry, with each one's value grammar, bounds, and whether applying it needs a restart. Parameter groups validate against this same catalog, so without it the only way to learn what is tunable is to submit a group and read the 400. Settings the platform owns are absent and are refused. Static platform metadata, not account-scoped. operationId: listEngineParameters parameters: - name: engine_type in: path required: true schema: type: string enum: - postgres - valkey responses: '200': description: OK content: application/json: schema: $ref: '#/components/schemas/EngineParameterListResponse' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/Forbidden' '404': $ref: '#/components/responses/NotFound' components: schemas: EngineParameterListResponse: type: object required: - engine - parameters properties: engine: type: string example: postgres parameters: type: array items: $ref: '#/components/schemas/EngineParameter' EngineParameter: type: object description: One setting a parameter group for this engine may carry. required: - name - kind - apply properties: name: type: string example: work_mem kind: type: string description: The value grammar this parameter accepts. enum: - integer - memory - duration - float - boolean - enum - pattern example: memory apply: type: string description: > What it costs to put the setting into effect. reload lands without dropping connections; restart takes effect only when the engine next restarts — the platform does not bounce a cluster for a config edit. enum: - reload - restart example: reload min: type: number description: Lower bound, in the parameter base unit. example: 0 max: type: number description: Upper bound, in the parameter base unit. example: 5000 values: type: array description: The legal settings, for enum and boolean parameters. items: type: string example: - none - ddl - mod - all pattern: type: string description: Regexp the value must match, for pattern parameters. Error: type: object required: - error properties: error: type: object required: - code - message - request_id properties: code: type: string description: Error code identifying the type of error example: INVALID_INPUT message: type: string description: Human-readable error message example: Invalid request parameters request_id: type: string format: uuid description: Request ID for debugging example: 550e8400-e29b-41d4-a716-446655440000 responses: BadRequest: description: Invalid request parameters content: application/json: schema: $ref: '#/components/schemas/Error' example: error: code: INVALID_INPUT message: Invalid request parameters request_id: 550e8400-e29b-41d4-a716-446655440000 Unauthorized: description: Authentication required or token invalid content: application/json: schema: $ref: '#/components/schemas/Error' example: error: code: UNAUTHORIZED message: Authentication required request_id: 550e8400-e29b-41d4-a716-446655440000 Forbidden: description: Insufficient permissions content: application/json: schema: $ref: '#/components/schemas/Error' example: error: code: ACCESS_DENIED message: You don't have permission to perform this action request_id: 550e8400-e29b-41d4-a716-446655440000 NotFound: description: Resource not found content: application/json: schema: $ref: '#/components/schemas/Error' example: error: code: NOT_FOUND message: Resource not found request_id: 550e8400-e29b-41d4-a716-446655440000 securitySchemes: SignatureAuth: type: apiKey in: header name: Authorization description: > Request signing with an access key issued to a service account. An HMAC-SHA256 over a canonical form of the request, close to AWS SigV4. The `basaltic` CLI signs for you. Send `Authorization`, `X-Date` (UTC, `YYYYMMDDTHHMMSSZ`) and `X-Nonce` (random per request); add `X-Content-Sha256` to bind a body, and `X-Amz-Security-Token` when using temporary credentials. ``` Authorization: BASALTIC-HMAC-SHA256 Credential=///basaltic/basaltic_request, SignedHeaders=host;x-date;x-nonce, Signature= ``` `` is the region code you are calling, or `global` for the global services. A signature is valid for 5 minutes from `X-Date`, and mutating requests are replay-guarded on the nonce. **Full signing procedure, including a working implementation:** https://docs.basaltic.sh/authentication ## Rate limits There is no global request budget. A limit applies only where an operation documents a `429`, and that operation says what it counts. Those responses carry `X-RateLimit-Limit`, `X-RateLimit-Remaining`, `X-RateLimit-Reset` and, on a `429`, `Retry-After` — read them rather than hard-coding a number. Retrying before `Retry-After` is refused and extends the window. Everything else is bounded by quota, not by request rate. ````