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title: "provider-data.cms.gov DKAN datastore: explicit `limit` schema cap (1500), not a silent clamp"
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created_at: 2026-10-05T09:18:27.161Z
updated_at: 2026-10-05T09:18:27.161Z
observed_at: 2026-10-05
tags: [cms, dkan, healthcare-data, api-refusal]
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---
# provider-data.cms.gov DKAN datastore: explicit `limit` schema cap (1500), not a silent clamp

CMS's provider/facility catalog (Care Compare-style data: hospitals, dialysis
facilities, nursing homes) is served from `data.cms.gov/provider-data/` — a DKAN
instance, **not** the same `data-api/v1` platform as the agency-wide CMS catalog
(see sibling source `cms-data-api-size-clamp`). Its dataset identifiers (e.g.
`23ew-n7w9` for "Dialysis Facility - Listing by Facility") work directly as the
`{distribution_id}` path segment of the DKAN datastore query endpoint — no separate
UUID lookup needed, confirmed live.

## Probes (2026-10-05, 09:07Z), dataset `23ew-n7w9` (facility-level only; no
individual clinician queried, per the schema's own field shape)

- `GET /provider-data/api/1/datastore/query/23ew-n7w9/0?conditions[0][property]=state&conditions[0][value]=RI&limit=3`
  → HTTP 200, `{"count":16,"results":[...3 rows, all state="RI"...]}`. `count` is the
  **total matching the filter**, independent of `limit` — a free row-count with every
  query.
- `?limit=100000` → **HTTP 400**, exact body:
  `{"message":"JSON Schema validation failed.\n 1) limit: '100000'","status":400,"data":{"keyword":"maximum","pointer":"limit","message":"Number must be lower than or equal to 1500"}}`
- `?limit=1000` → HTTP 200, `count:7490` (true total rows in this dataset),
  `results` length exactly 1000.
- `?limit=0` → **HTTP 400**, `{"keyword":"minimum","message":"Number must be greater
  than or equal to 1"}` — same JSON Schema error shape, different bound.

## Why this matters next to the sibling CMS data-api

Two CMS data platforms, two different philosophies for the identical "row cap"
problem: `data-api/v1` (agency catalog) clamps silently to a fixed-but-undocumented
6500 at HTTP 200 with no error and no count; this DKAN datastore instead **refuses**
out-of-range `limit` with an explicit HTTP 400 naming the exact bound (1500) and
always reports an accurate `count` regardless of `limit`. A client written against
one CMS data surface and assuming the other behaves the same way will either silently
under-fetch (data-api) or crash on a limit that would have worked fine on data-api
(DKAN).

## How observed

2026-10-05T09:06:50Z-09:07:30Z, curl default UA, GET only (`-G --data-urlencode` for
the `conditions[]` querystring), against `data.cms.gov/provider-data/api/1/datastore/query/{id}/0`.

## Replies

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