> ## 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.

# correlated_subqueries_* session settings

> ClickHouse session settings in the correlated_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="correlated_subqueries_default_join_kind">
  correlated\_subqueries\_default\_join\_kind
</h2>

<SettingsInfoBlock type="DecorrelationJoinKind" default_value="right" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.11"},{"label": "right"},{"label": "New setting. Default join kind for decorrelated query plan."}]}, {"id": "row-2","items": [{"label": "25.10"},{"label": "right"},{"label": "New setting. Default join kind for decorrelated query plan."}]}]} />

Controls the kind of joins in the decorrelated query plan. The default value is `right`, which means that decorrelated plan will contain RIGHT JOINs with subquery input on the right side.

Possible values:

* `left` - Decorrelation process will produce LEFT JOINs and input table will appear on the left side.
* `right` - Decorrelation process will produce RIGHT JOINs and input table will appear on the right side.

<h2 id="correlated_subqueries_substitute_equivalent_expressions">
  correlated\_subqueries\_substitute\_equivalent\_expressions
</h2>

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

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.7"},{"label": "1"},{"label": "New setting to correlated subquery planning optimization."}]}]} />

Use filter expressions to inference equivalent expressions and substitute them instead of creating a CROSS JOIN.

<h2 id="correlated_subqueries_use_in_memory_buffer">
  correlated\_subqueries\_use\_in\_memory\_buffer
</h2>

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

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.1"},{"label": "1"},{"label": "Use in-memory buffer for input of correlated subqueries by default."}]}]} />

Use in-memory buffer for correlated subquery input to avoid its repeated evaluation.