---
title: "Ingest settings"
summary: "Settings for how telemetry arrives and how it is batched before it is written."
description: "Telemetry batching and the default namespace."
status: preview
generated: true
read_when:
  - "Exporters cannot reach the instance."
  - "You are tuning write throughput or flush latency."
---

Every setting below is read once at startup and requires a restart to change.
Built-in defaults are overridden by nonempty environment values.
Unknown `FANOUT_` names fail startup; platform-injected service names are tolerated.
Vendor credentials and endpoints keep the vendor's documented names.

| Environment variable | Type | Default |
|---|---|---|
| `FANOUT_DEFAULT_NAMESPACE` | string | `default` |
| `FANOUT_INGEST_BATCH_SIZE` | integer | `50000` |
| `FANOUT_INGEST_MAX_IN_FLIGHT_BYTES` | integer | `268435456` |

## Notes

### `FANOUT_DEFAULT_NAMESPACE`

Supplies the namespace for telemetry without one.

### `FANOUT_INGEST_BATCH_SIZE`

Sets the group-commit row target; valid values are 1–50000. Individual requests remain atomic and can exceed this target.

### `FANOUT_INGEST_MAX_IN_FLIGHT_BYTES`

Caps decoded telemetry held across concurrent requests until durable publication. Zero is unbounded. A single request is admitted when no other request holds budget, even if it exceeds the limit.