> ## 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_* session settings

> ClickHouse session settings in the use_index_for_in_with_subqueries_* generated group.

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.settings](/docs/reference/system-tables/settings) and are autogenerated from [source](https://github.com/ClickHouse/ClickHouse/blob/master/src/Core/Settings.cpp).

<h2 id="use_index_for_in_with_subqueries">
  use\_index\_for\_in\_with\_subqueries
</h2>

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

Try using an index if there is a subquery or a table expression on the right side of the IN operator.

<h2 id="use_index_for_in_with_subqueries_max_values">
  use\_index\_for\_in\_with\_subqueries\_max\_values
</h2>

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

The maximum size of the set in the right-hand side of the IN operator to use table index for filtering. It allows to avoid performance degradation and higher memory usage due to the preparation of additional data structures for large queries. Zero means no limit.