# Create fields — POST /v1/o11y/logs/fields

URL: https://docs.hanzo.ai/docs/openapi/o11y/post-o11y-logs-fields

> Changes how one log field is stored — selects or deselects it as a materialized column and tunes its index — and echoes the setting back.

`POST /v1/o11y/logs/fields`

> [O11y →](https://docs.hanzo.ai/docs/openapi/o11y) · [All API references →](https://docs.hanzo.ai/docs/openapi) · [Get started →](https://docs.hanzo.ai/docs/guides)

|               |                                            |
| ------------- | ------------------------------------------ |
| **Address**   | `https://api.hanzo.ai/v1/o11y/logs/fields` |
| **Method**    | `POST`                                     |
| **Operation** | `post_o11y_logs_fields`                    |
| **Auth**      | `Authorization: Bearer $HANZO_API_KEY`     |

Changes how one log field is stored — selects or deselects it
as a materialized column and tunes its index — and echoes the setting back.

Callers need the editor role; the runtime's own gate enforces it.

## Request

6 fields, body `application/json` (required).

| Field              | In   | Type            | Required | Description                                                                                                       |
| ------------------ | ---- | --------------- | -------- | ----------------------------------------------------------------------------------------------------------------- |
| `dataType`         | body | string          | yes      | DataType is the field's data type, e.g. string, int64, float64, bool.                                             |
| `index`            | body | string          | —        | Index is the index expression to put on the column, e.g. minmax, set(N), bloom\_filter(P), tokenbf\_v1(S,H,SEED). |
| `indexGranularity` | body | integer (int64) | —        | IndexGranularity is the index granularity in rows.                                                                |
| `name`             | body | string          | yes      | Name is the field to tune.                                                                                        |
| `selected`         | body | boolean         | —        | Selected materializes the field as its own column when true.                                                      |
| `type`             | body | string          | yes      | Type is where the field lives: attributes or resources.                                                           |

## Response

| Status    | Body                  | Meaning           |
| --------- | --------------------- | ----------------- |
| `200`     | o11y.O11yFieldSetting | ok                |
| `202`     | Approval              | held for approval |
| `default` | problem-details       | refused           |

`200` body — 6 fields.

| Field              | In   | Type            | Always | Description                                                                                                       |
| ------------------ | ---- | --------------- | ------ | ----------------------------------------------------------------------------------------------------------------- |
| `dataType`         | body | string          | yes    | DataType is the field's data type, e.g. string, int64, float64, bool.                                             |
| `index`            | body | string          | —      | Index is the index expression to put on the column, e.g. minmax, set(N), bloom\_filter(P), tokenbf\_v1(S,H,SEED). |
| `indexGranularity` | body | integer (int64) | —      | IndexGranularity is the index granularity in rows.                                                                |
| `name`             | body | string          | yes    | Name is the field to tune.                                                                                        |
| `selected`         | body | boolean         | —      | Selected materializes the field as its own column when true.                                                      |
| `type`             | body | string          | yes    | Type is where the field lives: attributes or resources.                                                           |

Failure carries the platform error shape — see [Errors](https://docs.hanzo.ai/docs/errors).

## Examples

**CLI**

```bash
hanzo o11y logs fields create \
  --data-type <dataType> \
  --name <name> \
  --type <type>
```

**SDK**

**.ts**

```ts
import { Configuration, O11yApi } from 'hanzoai';

const api = new O11yApi(new Configuration({ accessToken: process.env.HANZO_API_KEY }));
const { data } = await api.postO11yLogsFields({ name: "<name>", dataType: "<dataType>", type: "<type>" });
```

**.py**

```python
from hanzoai.cloud import ApiClient, Configuration
from hanzoai.cloud.api import O11yApi

client = ApiClient(Configuration(access_token=os.environ["HANZO_API_KEY"]))
result = O11yApi(client).post_o11y_logs_fields(name="<name>", data_type="<dataType>", type="<type>")
```

**.go**

```go
cfg := hanzoai.NewConfiguration()
cfg.AddDefaultHeader("Authorization", "Bearer "+os.Getenv("HANZO_API_KEY"))
client := hanzoai.NewAPIClient(cfg)

resp, _, err := client.O11yAPI.PostO11yLogsFields(context.Background()).Execute()
if err != nil {
	return err
}
```

**.rs**

```rust
use hanzo_client::apis::{configuration::Configuration, o11y_api};

let mut cfg = Configuration::new();
cfg.bearer_access_token = std::env::var("HANZO_API_KEY").ok();

let result = o11y_api::post_o11y_logs_fields(&cfg, Default::default()).await?;
```

**.java**

```java
import ai.hanzo.cloud.ApiClient;
import ai.hanzo.cloud.api.O11yApi;

ApiClient client = new ApiClient();
client.setBearerToken(System.getenv("HANZO_API_KEY"));

var result = new O11yApi(client).postO11yLogsFields();
```

**HTTP**

```bash
curl -X POST https://api.hanzo.ai/v1/o11y/logs/fields \
  -H "Authorization: Bearer $HANZO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
       "name": "<name>",
       "dataType": "<dataType>",
       "type": "<type>"
     }'
```

**MCP**

MCP reaches **o11y** through the `o11y` tool, which names its 307 operations with its own verbs — this one among them, under a name only MCP declares. `describe` explains any of them:

```bash
curl -X POST https://api.hanzo.ai/v1/mcp \
  -H "Content-Type: application/json" \
  -d '{
       "jsonrpc": "2.0",
       "id": 1,
       "method": "tools/call",
       "params": {
         "name": "describe",
         "arguments": {
           "op": "list_o11y_autocomplete_aggregate_attributes"
         }
       }
     }'
```

---

[O11y API](https://docs.hanzo.ai/docs/openapi/o11y) · [All Hanzo APIs](https://docs.hanzo.ai/docs/openapi) · [Interactive reference](https://docs.hanzo.ai/docs/openapi/reference)