> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-parallel-read-in-order-multi-part.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

> Documentation for the JSONCompactEachRowWithProgress format

# JSONCompactEachRowWithProgress

| Input | Output | Alias |
| - | - | - |
| ✗ | ✔ | |

<h2 id="description">
  Description
</h2>

Combines the compact row-by-row output of [`JSONCompactEachRow`](/reference/formats/JSON/JSONCompactEachRow) with streaming progress information. ClickHouse streams each event as a separate JSON object; column values keep their native JSON types.

The related `JSONCompactStringsEachRowWithProgress` format uses the same top-level object kinds; field values are serialized as strings.

Shares the same stream contract as [`JSONEachRowWithProgress`](/reference/formats/JSON/JSONEachRowWithProgress) (`writesProgressConcurrently` / `finalizeImpl`), except that `row` / `totals` / `min` / `max` payloads are **arrays** of values in column order rather than named objects.

<h2 id="stream-objects">
  Stream objects
</h2>

Each line of the response is one JSON object. Clients should dispatch on the top-level key:

| Top-level key | When it appears | Shape |
| - | - | - |
| `meta` | Once, before the first `row` (a `progress` object may be emitted before it) | `{"meta":[{"name":...,"type":...}, ...]}` — column names and types |
| `row` | Once per result row | `{"row":[...]}` — column values in header order |
| `progress` | Periodically while the query runs | `{"progress":{...}}` — counters such as `read_rows`, `read_bytes`, `total_rows_to_read` |
| `totals` | When totals are present | `{"totals":[...]}` — totals row values in header order |
| `min` / `max` | When extremes are present | `{"min":[...]}` / `{"max":[...]}` — extreme row values in header order |
| `rows_before_limit_at_least` | When the query contains `LIMIT` | `{"rows_before_limit_at_least":N}` — lower estimate of rows there would have been without `LIMIT` (not proof that rows were dropped) |
| `rows_before_aggregation` | When the query performs aggregation and the `rows_before_aggregation` counter is enabled | `{"rows_before_aggregation":N}` |
| `exception` | When the query fails, on the HTTP path with `http_write_exception_in_output_format=1` | `{"exception":"..."}` — error text as a **top-level string**, not nested under `row` |

The `rows_before_limit_at_least` object is emitted when the query contains `LIMIT`, even if the limit did not drop any rows. It is a lower estimate of the number of rows there would have been without `LIMIT` (same meaning as in `JSON`); clients must not treat it as proof that rows were dropped.

`meta` is emitted once before the first `row`, but a `progress` object can arrive before `meta`. The top-level `exception` object is emitted on the HTTP path only when `http_write_exception_in_output_format=1`; otherwise the error surfaces through the transport. When emitted it is a separate top-level object, not nested under `row`.

<h2 id="example-usage">
  Example usage
</h2>

```sql title="Query" theme={null}
SELECT *
FROM generateRandom('a Array(Int8), d Decimal32(4), c Tuple(DateTime64(3), UUID)', 1, 10, 2)
LIMIT 5
FORMAT JSONCompactEachRowWithProgress
```

```response title="Response" theme={null}
{"meta":[{"name":"a","type":"Array(Int8)"},{"name":"d","type":"Decimal(9, 4)"},{"name":"c","type":"Tuple(DateTime64(3), UUID)"}]}
{"row":[[-8], 46848.5225, ["2064-06-11 14:00:36.578","b06f4fa1-22ff-f84f-a1b7-a5807d983ae6"]]}
{"row":[[-76], -85331.598, ["2038-06-16 04:10:27.271","2bb0de60-3a2c-ffc0-d7a7-a5c88ed8177c"]]}
{"row":[[-32], -31470.8994, ["2027-07-18 16:58:34.654","1cdbae4c-ceb2-1337-b954-b175f5efbef8"]]}
{"row":[[-116], 32104.097, ["1979-04-27 21:51:53.321","66903704-3c83-8f8a-648a-da4ac1ffa9fc"]]}
{"row":[[], 2427.6614, ["1980-04-24 11:30:35.487","fee19be8-0f46-149b-ed98-43e7455ce2b2"]]}
{"progress":{"read_rows":"5","read_bytes":"184","total_rows_to_read":"5","elapsed_ns":"335771"}}
{"rows_before_limit_at_least":5}
```

<h2 id="format-settings">
  Format settings
</h2>