---
title: hypertable_approximate_detailed_size() | Tiger Data Docs
description: Get detailed information about approximate disk space used by a hypertable
---

Since [2.14.0](https://github.com/timescale/timescaledb/releases/tag/2.14.0)

Get detailed information about approximate disk space used by a hypertable or continuous aggregate, returning size information for the table itself, any indexes on the table, any toast tables, and the total size of all. All sizes are reported in bytes.

When a continuous aggregate name is provided, the function transparently looks up the backing hypertable and returns its approximate size statistics instead.

Note

This function relies on the per backend caching using the in-built PostgreSQL storage manager layer to compute the approximate size cheaply. The PG cache invalidation clears off the cached size for a chunk when DML happens into it. That size cache is thus able to get the latest size in a matter of minutes. Also, due to the backend caching, any long running session will only fetch latest data for new or modified chunks and can use the cached data (which is calculated afresh the first time around) effectively for older chunks. Thus it is recommended to use a single connected PostgreSQL backend session to compute the approximate sizes of hypertables to get faster results.

For more information about using hypertables, including chunk size partitioning, see the [hypertable section](/docs/learn/hypertables/understand-hypertables/index.md).

## Samples

Get the approximate size information for a hypertable.

```
SELECT * FROM hypertable_approximate_detailed_size('hyper_table');
 table_bytes | index_bytes | toast_bytes | total_bytes
-------------+-------------+-------------+-------------
        8192 |       24576 |       32768 |       65536
```

## Arguments

The syntax is:

```
SELECT * FROM hypertable_approximate_detailed_size('<hypertable_name>');
```

| Name         | Type     | Default | Required | Description                                                              |
| ------------ | -------- | ------- | -------- | ------------------------------------------------------------------------ |
| `hypertable` | REGCLASS | -       | ✔        | Hypertable or continuous aggregate to show detailed approximate size of. |

## Returns

| Column       | Type   | Description                                                                                    |
| ------------ | ------ | ---------------------------------------------------------------------------------------------- |
| table\_bytes | BIGINT | Approximate disk space used by main\_table (like `pg_relation_size(main_table)`)               |
| index\_bytes | BIGINT | Approximate disk space used by indexes                                                         |
| toast\_bytes | BIGINT | Approximate disk space of toast tables                                                         |
| total\_bytes | BIGINT | Approximate total disk space used by the specified table, including all indexes and TOAST data |

Note

If executed on a relation that is not a hypertable, the function returns `NULL`.