> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-parallel-read-in-order-multi-part.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# iceberg_data_* 会话设置

> iceberg_data_* 生成分组中的 ClickHouse 会话设置。

export const VersionHistory = ({rows = []}) => {
  if (rows.length === 0) {
    return null;
  }
  const headers = ["版本", "默认值", "注释"];
  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
  }}>
        版本历史
      </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
  }}>类型</div>
      <div style={{
    overflowWrap: "anywhere"
  }}>{type}</div>
      <div style={{
    fontWeight: 600,
    opacity: 0.72,
    marginInlineStart: "0.5rem"
  }}>默认值</div>
      <div style={{
    overflowWrap: "anywhere"
  }}>{default_value}</div>
      {changeable_without_restart && <div style={{
    fontWeight: 600,
    opacity: 0.72,
    marginInlineStart: "0.5rem"
  }}>
          无需重启即可更改
        </div>}
      {changeable_without_restart && <div style={{
    overflowWrap: "anywhere"
  }}>
          {changeable_without_restart}
        </div>}
    </div>;
};

这些设置可在 [system.settings](/zh/reference/system-tables/settings) 中查看，并由 [源代码](https://github.com/ClickHouse/ClickHouse/blob/master/src/Core/Settings.cpp) 自动生成。

<h2 id="iceberg_data_file_size_lower_threshold_compaction">
  iceberg\_data\_file\_size\_lower\_threshold\_compaction
</h2>

<SettingsInfoBlock type="UInt64" default_value="402653184" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.9"},{"label": "402653184"},{"label": "与 Iceberg `rewrite_data_files` 存储过程推导 `min-file-size-bytes` 的方式保持一致：取目标文件大小（512 MiB）的 0.75 倍。合并整理现在选取小于 384 MiB 的文件，而非小于 10 MiB 的文件。"}]}, {"id": "row-2","items": [{"label": "26.5"},{"label": "10485760"},{"label": "新增设置"}]}]} />

小于该值的数据文件会被选中进行合并整理。

默认值为 Iceberg 表属性 `write.target-file-size-bytes` 文档默认值 (512 MiB) 的 `0.75` 倍，这也是 `rewrite_data_files` 存储过程推导其 `min-file-size-bytes` 选项的方式，
参见 [https://iceberg.apache.org/docs/1.5.2/configuration/。](https://iceberg.apache.org/docs/1.5.2/configuration/。)

<h2 id="iceberg_data_file_size_upper_threshold_compaction">
  iceberg\_data\_file\_size\_upper\_threshold\_compaction
</h2>

<SettingsInfoBlock type="UInt64" default_value="966367641" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.9"},{"label": "966367641"},{"label": "与 Iceberg `rewrite_data_files` 存储过程推导 `max-file-size-bytes` 的方式保持一致：目标文件大小（512 MiB）的 1.8 倍。"}]}, {"id": "row-2","items": [{"label": "26.5"},{"label": "10737418240"},{"label": "新增设置"}]}]} />

超过该大小的数据文件会被选中进行合并整理。

默认值为 Iceberg 表属性 `write.target-file-size-bytes` 文档中所载默认值 (512 MiB) 的 `1.8` 倍，`rewrite_data_files` 存储过程也是以这种方式推导其 `max-file-size-bytes` 选项的，
参见 [https://iceberg.apache.org/docs/1.5.2/configuration/。](https://iceberg.apache.org/docs/1.5.2/configuration/。)