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

# compress_* MergeTree table settings

> ClickHouse MergeTree table settings in the compress_* generated group.

export const SettingsInfoBlock = ({type, default_value, changeable_without_restart}) => {
  return <div className="not-prose" style={{
    display: "flex",
    flexWrap: "wrap",
    alignItems: "baseline",
    columnGap: "0.5rem",
    rowGap: "0.125rem",
    margin: "0.375rem 0",
    fontSize: "0.8125rem",
    lineHeight: "1.125rem"
  }}>
      <div style={{
    fontWeight: 600,
    opacity: 0.72
  }}>Type</div>
      <div style={{
    overflowWrap: "anywhere"
  }}>{type}</div>
      <div style={{
    fontWeight: 600,
    opacity: 0.72,
    marginInlineStart: "0.5rem"
  }}>Default</div>
      <div style={{
    overflowWrap: "anywhere"
  }}>{default_value}</div>
      {changeable_without_restart && <div style={{
    fontWeight: 600,
    opacity: 0.72,
    marginInlineStart: "0.5rem"
  }}>
          Changeable without restart
        </div>}
      {changeable_without_restart && <div style={{
    overflowWrap: "anywhere"
  }}>
          {changeable_without_restart}
        </div>}
    </div>;
};

These settings are available in [system.merge\_tree\_settings](/docs/reference/system-tables/merge_tree_settings) and are autogenerated from ClickHouse source.

<h2 id="compress_marks">
  compress\_marks
</h2>

<SettingsInfoBlock type="Bool" default_value="1" />

Marks support compression, reduce mark file size and speed up network
transmission.

<h2 id="compress_per_column_in_compact_parts">
  compress\_per\_column\_in\_compact\_parts
</h2>

<SettingsInfoBlock type="Bool" default_value="1" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.4"},{"label": "1"},{"label": "New setting"}]}]} />

Controls the physical layout of Compact parts. If true (default), each column in a granule
starts a new compressed block, allowing ClickHouse to skip reading unnecessary columns
from disk. If false, all columns within a granule are packed into the same compressed block,
improving compression ratio but requiring more data to be decompressed during reads.
This is beneficial for workloads that always read all columns (e.g. projections).

<h2 id="compress_primary_key">
  compress\_primary\_key
</h2>

<SettingsInfoBlock type="Bool" default_value="1" />

Primary key support compression, reduce primary key file size and speed up
network transmission.