# Unable load big json data to Iceberg with Dremio

**URL:** https://community.dremio.com/t/unable-load-big-json-data-to-iceberg-with-dremio/12878
**Category:** Apache Iceberg
**Created:** [March 18, 2025, 11:01am UTC](https://community.dremio.com/t/unable-load-big-json-data-to-iceberg-with-dremio/12878 "2025-03-18T11:01:16Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![sleepdan](https://avatars.discourse-cdn.com/v4/letter/s/74df32/32.png) [@sleepdan](https://community.dremio.com/u/sleepdan)
#### Post date: [March 18, 2025, 11:01am UTC](https://community.dremio.com/t/unable-load-big-json-data-to-iceberg-with-dremio/12878/1 "2025-03-18T11:01:16Z")

</div>

Hi all!  
I want to load data from a json file that I have previously loaded into minio bucket. I added a data source and the loaded data is displayed (file “bigdata.json”):

 ![image](https://us1.discourse-cdn.com/flex020/uploads/dremio/original/2X/3/30ba23b9ccaef3f48b69796a100ca123e027650b.png)  
and content data of file is previewed.

When i create table with schema:

```auto
CREATE TABLE nessie.test_data1 (id INT,	firstName VARCHAR,	lastName VARCHAR,	gender VARCHAR,	address VARCHAR, city VARCHAR,	phone VARCHAR,	email VARCHAR,	status VARCHAR,	createdDate TIMESTAMP);

```

But if I try to run the command:

```auto
COPY INTO nessie."test_data1"
FROM '@sampledata/bigdata.json'
FILE_FORMAT 'json' (TIMESTAMP_FORMAT 'YYYY-MM-DD"T"HH24:MI:SS.FFF');

```

i got an error on UI:

> Dremio attempted to unwrap a toplevel list in your document. However, it appears that there is trailing content after this top level list. Dremio only supports querying a set of distinct maps or a single json array with multiple inner maps.

My json data looks like this:

```auto
[
  {
    "id": 1,
    "firstName": "Gonzalo",
    "lastName": "Cassin",
    "gender": "male",
    "address": "04355 Grady Summit",
    "city": "Mayertborough",
    "phone": "501-294-290",
    "email": "Freda.Mitchell@yahoo.com",
    "status": "Available",
    "createdDate": "2020-01-01T11:18:51.591"
  },
  {
    "id": 2,
    "firstName": "Alexie",
    "lastName": "Fisher",
    "gender": "female",
    "address": "7363 Murphy Run",
    "city": "East Jonathon",
    "phone": "501-668-320",
    "email": "Harrison55@gmail.com",
    "status": "Offline",
    "createdDate": "2020-01-01T11:19:51.591"
  },
.... billion items on one array
]

```

Total size of json file is 2.7 Gb.

The structure of my json file meets the requirements specified in the error - “or a single json array with multiple inner maps”.

For the experiment, I took json of exactly the same structure, but with only a few elements in the array, and this data was successfully loaded into the table using exactly the same query.

BUT why can’t I upload a large file to the iceberg table? Dremio can’t work with BigData?!