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supabase/apps/reference/docs/guides/platform/disk-usage.mdx
2022-10-05 20:31:31 +08:00

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---
id: disk-usage
title: Disk space usage
description: Learn how database disk space usage is reported.
---
Database disk space usage refers to the _monthly average disk usage_, as reported by Postgres. This metric is reported in your project's [billing page](https://app.supabase.com/project/_/settings/billing) and is updated daily.
For an instantaneous live view of the DB disk space being used by your project, you can execute in Postgres:
```sql
SELECT SUM(pg_database_size(pg_database.datname)) / (1024 * 1024) as db_size_mb FROM pg_database;
```
This value is also reported in the [database settings page](https://app.supabase.com/project/_/settings/database).
## Vacuum operations
Postgres does not immediately reclaim the physical space used by dead tuples (i.e., deleted rows) in the DB. Instead, they are internally marked as removed until a [vacuum operation](https://www.postgresql.org/docs/current/routine-vacuuming.html) is executed. As a result, deleting data from your DB may not immediately reduce the reported disk usage.
:::note
Vacuum operations can temporarily increase resource utilization, which can adversely impact the observed performance of your project until the maintenance is completed.
:::
Supabase projects have automatic vacuuming enabled, which ensures that these operations are performed regularly to keep the database healthy and performant. However, it can be necessary to either [fine-tune](https://www.percona.com/blog/2018/08/10/tuning-autovacuum-in-postgresql-and-autovacuum-internals/) [the autovacuum parameters](https://www.enterprisedb.com/blog/postgresql-vacuum-and-analyze-best-practice-tips), or [manually initiate](https://www.postgresql.org/docs/current/sql-vacuum.html) vacuum operations. For example, running a manual vacuum after deleting large amounts of data from your DB could help reduce the reported disk usage by Postgres.