> ## 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.

# use_index_for_in_with_subqueries_* 会话设置

> ClickHouse 在 use_index_for_in_with_subqueries_* 自动生成分组中的会话设置。

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>;
};

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="use_index_for_in_with_subqueries">
  ## use\_index\_for\_in\_with\_subqueries
</div>

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

如果 IN 运算符右侧为子查询或表表达式，则尝试使用索引。

<div id="use_index_for_in_with_subqueries_max_values">
  ## use\_index\_for\_in\_with\_subqueries\_max\_values
</div>

<SettingsInfoBlock type="UInt64" default_value="0" />

在 IN 运算符右侧的集合中，可用于借助表索引进行过滤的最大大小。这样可以避免大型查询因准备额外数据结构而导致性能下降和内存占用增加。0 表示不受限制。