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

# Incremental Syncs

Syncmaven supports incremental syncs. This means that subsequent syncs will only fetch the data
that has changed since the last sync. Plus, it supports checkpointing via same mechanism. If
long-running sync fails in the middle, the next run will carry on from where it left off.

# Cursors

The main mechanism for incremental syncs is cursors. A cursor is a field in [model](/docs/models) that
only grows over time. For example, `updated_at` field in a table is a good candidate for cursor, or
`id` if it is auto-incrementing.

Cursors are defined in [model](/fundamentals/models)

```sql theme={null}
--{{ config "name" "Users" }}
--{{ config "datasource" env.DATABASE_URL }}
--{{ config "cursor" "updated_at" }}

select * from users where :cursor is null or updated_at >= :cursor
```

In the model configuration above, cursor is defined as `updated_at`. The model will only fetch rows where `update_at`
value is greater than the last `cursor` value, which is stored in the [sync state](/fundamentals/state) and
referenced by `:cursor` in the query.

<Info>
  For the first runs, and full refreshes, the cursor value will be `null`. It means that all rows will be fetched.
  So the query should be able to handle `null` cursor value properly, note the `:cursor is null` part in the query.
</Info>

## Checkpointing

The same mechanism is used for checkpointing. Sync will save a cursor value periodically, after a batch of 100
rows by default. If the sync fails in the middle, the next run will start from the last saved cursor value.