> ## Documentation Index
> Fetch the complete documentation index at: https://docs.telophasehq.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview

> Write processed records to storage systems or discard them.

Sinks define **where Tangent writes data to** — for example, S3 buckets, local files, or testing targets like `blackhole`.\
They are the **terminal nodes** of the DAG: after records are processed by plugins, they are serialized and written by sinks.

***

## Sink Types

| Type                                          | Description                                    | Example                        |
| --------------------------------------------- | ---------------------------------------------- | ------------------------------ |
| [`s3`](/configuration/sinks/s3)               | Write to Amazon S3 buckets with WAL durability | `my-bucket`                    |
| [`file`](/configuration/sinks/file)           | Write to local or mounted filesystem paths     | `/var/lib/tangent/output.json` |
| [`blackhole`](/configuration/sinks/blackhole) | Discard output (useful for testing)            | —                              |

***

## Common Configuration

<ParamField path="type" type="string" required>
  Selects the sink type.\
  One of: `s3`, `file`, or `blackhole`.
</ParamField>

<ParamField path="encoding" type="object">
  Controls how Tangent serializes records before writing.\
  See [Encoding](/configuration/sinks/encoding) for supported formats (`ndjson`, `json`, `avro`, `parquet`).
</ParamField>

<ParamField path="compression" type="object">
  Configures compression for sink objects.\
  See [Compression](/configuration/sinks/compression) for algorithm details and levels.
</ParamField>

***

## Example (S3 Sink)

```yaml tangent.yaml icon=upload theme={null}
sinks:
  s3_main:
    type: s3
    bucket_name: my-bucket
    region: us-west-2
    encoding:
      type: parquet
      schema: ./schemas/arrow_schema.json
    compression:
      type: gzip
      level: 6
```

***

## Behavior

* Each sink manages its own WAL and upload queue.
* Data rotation happens automatically based on time or size thresholds.
* Tangent guarantees **at-least-once delivery** — WALs ensure safe recovery on restart.
* Encoding and compression are handled transparently before upload.

***

## See also

* [S3 Sink](/configuration/sinks/s3)
* [File Sink](/configuration/sinks/file)
* [Blackhole Sink](/configuration/sinks/blackhole)
* [Encoding](/configuration/sinks/encoding)
* [Compression](/configuration/sinks/compression)
* [DAG](/configuration/dag)