> ## 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.

# ast_fuzzer_* 会话设置

> ClickHouse ast_fuzzer_* 分组中的会话设置。

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>;
};

export const ExperimentalBadge = () => {
  return <div className="experimentalBadge">
            <div className="experimentalIcon">
            <svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg">
                <path strokeWidth="1.25" d="M5.5 2H10.5" stroke="currentColor" strokeLinecap="round" strokeLinejoin="round" />
                <path strokeWidth="1.25" d="M9.50015 2V6.19625L13.4283 12.7425C13.4738 12.8183 13.4985 12.9049 13.4996 12.9934C13.5008 13.0818 13.4785 13.169 13.435 13.246C13.3914 13.323 13.3283 13.3871 13.2519 13.4317C13.1755 13.4764 13.0886 13.4999 13.0002 13.5H3.00015C2.91164 13.5 2.8247 13.4766 2.74822 13.432C2.67174 13.3874 2.60847 13.3233 2.56487 13.2463C2.52126 13.1693 2.49889 13.082 2.50004 12.9935C2.50119 12.905 2.52582 12.8184 2.5714 12.7425L6.50015 6.19625V2" stroke="currentColor" strokeLinecap="round" strokeLinejoin="round" />
                <path strokeWidth="1.25" d="M4.47656 9.56754C5.30344 9.41254 6.47656 9.47942 7.99969 10.25C10.0153 11.2707 11.4216 11.0569 12.2184 10.7282" stroke="currentColor" strokeLinecap="round" strokeLinejoin="round" />
            </svg>
        </div>
            Experimental 功能。 <u><a href="/docs/docs/beta-and-experimental-features#experimental-features">了解详情。</a></u>
        </div>;
};

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

<div id="ast_fuzzer_any_query">
  ## ast\_fuzzer\_any\_query
</div>

<ExperimentalBadge />

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

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.2"},{"label": "0"},{"label": "新增设置：允许对所有查询类型进行 fuzzing，而不仅限于只读查询。"}]}]} />

当为 false (默认值) 时，服务器端 AST fuzzer (由 `ast_fuzzer_runs` 控制) 仅对只读查询 (SELECT、EXPLAIN、SHOW、DESCRIBE、EXISTS) 进行 fuzzing。当为 true 时，则会对所有查询类型进行 fuzzing，包括 DDL 和 INSERT。

<div id="ast_fuzzer_runs">
  ## ast\_fuzzer\_runs
</div>

<ExperimentalBadge />

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

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.2"},{"label": "0"},{"label": "用于启用服务器端 AST fuzzer 的新设置。"}]}]} />

启用服务器端 AST fuzzer。它会在每次普通查询后运行随机查询，并丢弃其结果。

* 0：禁用 (默认) 。
* 大于 0 且小于 1 的值 (exclusive) ：运行单个模糊测试查询的概率。
* 值 >= 1：每次普通查询要运行的模糊测试查询数量。

fuzzer 会跨所有会话累积来自全部查询的 AST 片段，并随着时间推移生成越来越有意思的变体。执行失败的模糊测试查询会被静默丢弃；结果绝不会返回给客户端。