# Garbage Collection

## How garbage is created

Doltgres creates on disk garbage. Doltgres transactions that do not have a corresponding Doltgres commit create on disk garbage. This garbage is most noticeable after large data imports.

Specifically, writes to Doltgres can result in multiple chunks of the [prolly\
tree](https://www.dolthub.com/blog/2020-04-01-how-dolt-stores-table-data) being rewritten,\
which [writes a large portion of the\
tree](https://www.dolthub.com/blog/2020-05-13-dolt-commit-graph-and-structural-sharing/#cant_share).\
When you perform write operations without committing or delete a branch containing novel\
chunks, garbage is created.

![How garbage is created](/files/louPYMUHgfB79pRVbEo3)

### Online

You can run garbage collection on your running SQL server using [`select dolt_gc`](/reference/version-control/dolt-sql-functions.md#dolt_gc) through any connected client.

NOTE: Performing GC on [a cluster replica](/reference/server/replication.md) which is in standby mode is not\
yet supported, and running `select dolt_gc()` on the replica will fail.

## Automated GC

Automated garbage collection is currently experimental and will be enabled by default in a release\
later this year. Check back for details.


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