> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-postgresql-tls-support.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# cache_populated_by_fetch_* MergeTree table settings

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

export const VersionHistory = ({rows = []}) => {
  if (rows.length === 0) {
    return null;
  }
  const headers = ["Version", "Default value", "Comment"];
  const border = "1px solid rgba(128, 128, 128, 0.3)";
  const cell = {
    border,
    padding: "0.25rem 0.5rem",
    textAlign: "start",
    verticalAlign: "top"
  };
  return <details className="not-prose" style={{
    border,
    borderRadius: "0.5rem",
    margin: "0.5rem 0",
    padding: "0.5rem 0.75rem",
    fontSize: "0.8125rem",
    lineHeight: "1.125rem"
  }}>
      <summary style={{
    cursor: "pointer",
    fontWeight: 600,
    opacity: 0.72
  }}>
        Version history
      </summary>
      <table style={{
    borderCollapse: "collapse",
    width: "100%",
    margin: "0.5rem 0 0"
  }}>
        <thead>
          <tr>
            {headers.map(header => <th key={header} style={{
    ...cell,
    fontWeight: 600,
    opacity: 0.72
  }}>
                {header}
              </th>)}
          </tr>
        </thead>
        <tbody>
          {rows.map((row, row_index) => <tr key={row.id ?? row_index}>
              {(row.items ?? []).map((item, item_index) => <td key={item_index} style={{
    ...cell,
    overflowWrap: "anywhere"
  }}>
                  {item?.label}
                </td>)}
            </tr>)}
        </tbody>
      </table>
    </details>;
};

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](/reference/system-tables/merge_tree_settings) and are autogenerated from ClickHouse source.

<h2 id="cache_populated_by_fetch">
  cache\_populated\_by\_fetch
</h2>

<SettingsInfoBlock type="Bool" default_value="0" />

<Note>
  This setting applies only to ClickHouse Cloud.
</Note>

When `cache_populated_by_fetch` is disabled (the default setting), new data
parts are loaded into the filesystem cache only when a query is run that requires
those parts.

If enabled, `cache_populated_by_fetch` will instead cause all nodes to load
new data parts from storage into their filesystem cache without requiring a query
to trigger such an action.

**See Also**

* [ignore\_cold\_parts\_seconds](/reference/settings/session-settings/ignore#ignore_cold_parts_seconds)
* [prefer\_warmed\_unmerged\_parts\_seconds](/reference/settings/session-settings/prefer#prefer_warmed_unmerged_parts_seconds)
* [cache\_warmer\_threads](/reference/settings/session-settings/other#cache_warmer_threads)

<h2 id="cache_populated_by_fetch_filename_regexp">
  cache\_populated\_by\_fetch\_filename\_regexp
</h2>

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.6"},{"label": ""},{"label": "New setting"}]}]} />

<Note>
  This setting applies only to ClickHouse Cloud.
</Note>

If not empty, only files that match this regex will be prewarmed into the cache after fetch (if `cache_populated_by_fetch` is enabled).