> ## 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.

# create_* session settings

> ClickHouse session settings in the create_* 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="create_if_not_exists">
  create\_if\_not\_exists
</h2>

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

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.9"},{"label": "0"},{"label": "New setting."}]}]} />

Enable `IF NOT EXISTS` for `CREATE` statement by default. If either this setting or `IF NOT EXISTS` is specified and a table with the provided name already exists, no exception will be thrown.

<h2 id="create_index_ignore_unique">
  create\_index\_ignore\_unique
</h2>

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

Ignore UNIQUE keyword in CREATE UNIQUE INDEX. Made for SQL compatibility tests.

<h2 id="create_replicated_merge_tree_fault_injection_probability">
  create\_replicated\_merge\_tree\_fault\_injection\_probability
</h2>

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

The probability of a fault injection during table creation after creating metadata in ZooKeeper

<h2 id="create_table_empty_primary_key_by_default">
  create\_table\_empty\_primary\_key\_by\_default
</h2>

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

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.11"},{"label": "1"},{"label": "Better usability"}]}]} />

Allow to create \*MergeTree tables with empty primary key when ORDER BY and PRIMARY KEY not specified