> ## 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.

# http_headers_* 会话设置

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

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](/docs/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。

<div id="http_headers_progress_interval_ms">
  ## http\_headers\_progress\_interval\_ms
</div>

<SettingsInfoBlock type="UInt64" default_value="100" />

发送 HTTP 请求头 X-ClickHouse-Progress 的频率不得超过指定的时间间隔。

<div id="http_headers_read_timeout">
  ## http\_headers\_read\_timeout
</div>

<SettingsInfoBlock type="秒" default_value="30" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.4"},{"label": "30"},{"label": "用于限制读取所有 HTTP 请求头总耗时的新设置，可防御 slowloris 攻击。"}]}]} />

读取全部 HTTP 请求头的最长时间 (以秒为单位) 。这是整个请求头解析阶段的总时限，而不是单次读取超时。它可防御 slowloris 类攻击，即客户端通过极其缓慢地发送请求头数据来长期占用连接。