> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify-poc.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Create a compression policy

> Compress your data automatically, based on the conditions you set

export const HYPERTABLE = 'hypertable';

<Icon icon="archive" iconType="duotone" /> Old API since [2.18.0][tsdb-2.18.0]. Superseded by [Optimize your data for
real-time analytics][hypercore-optimize]. However, compression APIs are still supported, you do not need to migrate to
the hypercore APIs.

You can enable compression on individual {HYPERTABLE}s, by declaring which column you want to segment by.

## Enable a compression policy

This page uses an example table, called `example`, and segments it by the `device_id` column. Every chunk that is more
than seven days old is then marked to be automatically compressed. The source data is organized like this:

| time           | device\_id | cpu   | disk\_io | energy\_consumption |
| -------------- | ---------- | ----- | -------- | ------------------- |
| 8/22/2019 0:00 | 1          | 88.2  | 20       | 0.8                 |
| 8/22/2019 0:05 | 2          | 300.5 | 30       | 0.9                 |

1. **Alter the table**

   At the `psql` prompt, alter the table:

   ```sql theme={"dark"}
   ALTER TABLE example SET (
     timescaledb.compress,
     timescaledb.compress_segmentby = 'device_id'
   );
   ```

2. **Add a compression policy**

   Add a compression policy to compress chunks that are older than seven days:

   ```sql theme={"dark"}
   SELECT add_compression_policy('example', INTERVAL '7 days');
   ```

For more information, see the API reference for [`ALTER TABLE (compression)`][alter-table-compression] and
[`add_compression_policy`][add_compression_policy].

## View current compression policy

To view the compression policy that you've set:

```sql theme={"dark"}
SELECT * FROM timescaledb_information.jobs
  WHERE proc_name='policy_compression';
```

For more information, see the API reference for [`timescaledb_information.jobs`][informational-views].

## Pause compression policy

To disable a compression policy temporarily, find the corresponding job ID and then call `alter_job` to pause it:

```sql theme={"dark"}
SELECT * FROM timescaledb_information.jobs where proc_name = 'policy_compression' AND relname = 'example'
```

```sql theme={"dark"}
SELECT alter_job(<job_id>, scheduled => false);
```

To enable it again:

```sql theme={"dark"}
SELECT alter_job(<job_id>, scheduled => true);
```

## Remove compression policy

To remove a compression policy, use `remove_compression_policy`:

```sql theme={"dark"}
SELECT remove_compression_policy('example');
```

For more information, see the API reference for [`remove_compression_policy`][remove_compression_policy].

## Disable compression

You can disable compression entirely on individual {HYPERTABLE}s. This command works only if you don't currently have any
compressed chunks:

```sql theme={"dark"}
ALTER TABLE <EXAMPLE> SET (timescaledb.compress=false);
```

If your {HYPERTABLE} contains compressed chunks, you need to [decompress each chunk][decompress-chunks] individually
before you can turn off compression.

[add_compression_policy]: /api-reference/timescaledb/compression/add_compression_policy

[alter-table-compression]: /api-reference/timescaledb/compression/alter_table_compression

[decompress-chunks]: /manage-data/capabilities/compression/decompress-chunks

[hypercore-optimize]: /manage-data/capabilities/hypercore/real-time-analytics-in-hypercore

[informational-views]: /api-reference/timescaledb/informational-views/jobs

[remove_compression_policy]: /api-reference/timescaledb/compression/remove_compression_policy

[tsdb-2.18.0]: https://github.com/timescale/timescaledb/releases/tag/2.18.0