---
title: Engine settings reference
meta:
    description: Settings for Tinybird table engines
---

# Engine settings

You can customize table engine settings to better match your needs.

The engine options are: `engine_partition_key`, `engine_sorting_key`, `engine_primary_key`, `engine_sampling_key`, `engine_ttl` and `engine_settings`.

If `engine_partition_key` is empty or not passed as a parameter, the underlying Data Source doesn't have any partition unless there's a `Date` column. In that case the Data Source is partitioned by year. If you want to create a Data Source with no partitions, send `engine_partition_key=tuple()`.

{% callout type="caution" %}
Don't change the following settings unless you are familiar with them and understand their impact. If you're unsure, contact Tinybird at <support@tinybird.co> or in the [Community Slack](/community).
{% /callout %}

The supported engine settings are:

- `index_granularity`
- `merge_with_ttl_timeout`
- `ttl_only_drop_parts`
- `min_bytes_for_wide_part`
- `min_rows_for_wide_part`
- `min_age_to_force_merge_seconds`
- `min_age_to_force_merge_on_partition_only`
- `enable_replacing_merge_with_cleanup_for_min_age_to_force_merge`

## index_granularity

Maximum number of data rows between the marks of an index.

Default value: 8192.

## merge_with_ttl_timeout

Minimum delay in seconds before repeating a merge with delete TTL.

Default value: `14400` seconds (4 hours).

## ttl_only_drop_parts

Controls whether data parts are fully dropped in MergeTree tables when all rows in that part have expired according to their `TTL` settings.

When `ttl_only_drop_parts` is disabled (by default), only the rows that have expired based on their TTL settings are removed.

When `ttl_only_drop_parts` is enabled, the entire part is dropped if all rows in that part have expired according to their `TTL` settings.

Default value: 0.

## min_bytes_for_wide_part

Minimum number of bytes/rows in a data part that can be stored in `Wide` format.
You can set one, both or none of these settings.

## min_age_to_force_merge_seconds

Minimum age of a part in seconds before it becomes eligible for forced merging. Useful for `ReplacingMergeTree` tables where you want to ensure old parts are merged and deduplicated within a predictable time window.

Default value: 0 (disabled).

## min_age_to_force_merge_on_partition_only

When enabled, `min_age_to_force_merge_seconds` only applies to whole partitions rather than individual parts.

Default value: 0 (disabled).

## enable_replacing_merge_with_cleanup_for_min_age_to_force_merge

When enabled alongside `min_age_to_force_merge_seconds` on a `ReplacingMergeTree`, forced merges also clean up obsolete rows (duplicates that have been replaced). Without this setting, forced merges compact parts but don't remove old versions.

Default value: 0 (disabled).

Example combining these settings in a `.datasource` file:

```
ENGINE "ReplacingMergeTree"
ENGINE_SORTING_KEY "id"
ENGINE_SETTINGS "min_age_to_force_merge_seconds=10,enable_replacing_merge_with_cleanup_for_min_age_to_force_merge=1"
```