> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-trino-dialect.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# mysql_* session settings

> ClickHouse session settings in the mysql_* generated group.

export const VersionHistory = ({rows = []}) => {
  if (rows.length === 0) {
    return null;
  }
  const headers = ["Version", "Default value", "Comment"];
  const border = "1px solid rgba(128, 128, 128, 0.3)";
  const cell = {
    border,
    padding: "0.25rem 0.5rem",
    textAlign: "start",
    verticalAlign: "top"
  };
  return <details className="not-prose" style={{
    border,
    borderRadius: "0.5rem",
    margin: "0.5rem 0",
    padding: "0.5rem 0.75rem",
    fontSize: "0.8125rem",
    lineHeight: "1.125rem"
  }}>
      <summary style={{
    cursor: "pointer",
    fontWeight: 600,
    opacity: 0.72
  }}>
        Version history
      </summary>
      <table style={{
    borderCollapse: "collapse",
    width: "100%",
    margin: "0.5rem 0 0"
  }}>
        <thead>
          <tr>
            {headers.map(header => <th key={header} style={{
    ...cell,
    fontWeight: 600,
    opacity: 0.72
  }}>
                {header}
              </th>)}
          </tr>
        </thead>
        <tbody>
          {rows.map((row, row_index) => <tr key={row.id ?? row_index}>
              {(row.items ?? []).map((item, item_index) => <td key={item_index} style={{
    ...cell,
    overflowWrap: "anywhere"
  }}>
                  {item?.label}
                </td>)}
            </tr>)}
        </tbody>
      </table>
    </details>;
};

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

<h2 id="mysql_datatypes_support_level">
  mysql\_datatypes\_support\_level
</h2>

<SettingsInfoBlock type="MySQLDataTypesSupport" default_value="decimal,datetime64,date2Date32,geometry" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.7"},{"label": "decimal,datetime64,date2Date32,geometry"},{"label": "Map MySQL's concrete spatial types (LINESTRING, POLYGON, MULTILINESTRING, MULTIPOLYGON, MULTIPOINT) and the generic GEOMETRY type to the corresponding ClickHouse geometric types by default. The generic GEOMETRY column maps to the umbrella Geometry type; reading a value whose subtype has no ClickHouse counterpart (GEOMETRYCOLLECTION) throws at read time."}]}, {"id": "row-2","items": [{"label": "26.3"},{"label": "decimal,datetime64,date2Date32"},{"label": "Enable modern MySQL type mappings by default."}]}]} />

Defines how MySQL types are converted to corresponding ClickHouse types. A comma separated list in any combination of `decimal`, `datetime64`, `date2Date32`, `date2String` or `geometry`. All modern mappings (`decimal`, `datetime64`, `date2Date32`, `geometry`) are enabled by default.

* `decimal`: convert `NUMERIC` and `DECIMAL` types to `Decimal` when precision allows it.
* `datetime64`: convert `DATETIME` and `TIMESTAMP` types to `DateTime64` instead of `DateTime` when precision is not `0`.
* `date2Date32`: convert `DATE` to `Date32` instead of `Date`. Takes precedence over `date2String`.
* `date2String`: convert `DATE` to `String` instead of `Date`. Overridden by `datetime64`.
* `geometry`: convert MySQL's spatial types (`LINESTRING`, `POLYGON`, `MULTILINESTRING`, `MULTIPOLYGON`, `MULTIPOINT`) to the corresponding ClickHouse geometric types, and the generic `GEOMETRY` type to the umbrella `Geometry` type. `POINT` is always converted to `Point` regardless of this option. Because a generic `GEOMETRY` column can hold any subtype, reading a value whose subtype has no ClickHouse counterpart (`GEOMETRYCOLLECTION`) throws an exception at read time; columns declared as `GEOMETRYCOLLECTION` map to `String`. A nullable spatial column other than `POINT` also maps to `Nullable(String)`, since `Point` is the only geometric type that can be nested inside `Nullable`. Every such string is a 4-byte SRID prefix followed by the WKB payload, as returned by MySQL. All of the above applies when the schema is inferred from the column types of a MySQL table; when the source is a query (the `query(...)` argument of the `mysql` table function or the `MySQL` table engine), MySQL reports every spatial result column as the generic `GEOMETRY` without the concrete subtype, so such columns — including `POINT` — map to `String` (`Nullable(String)` if nullable).

<h2 id="mysql_max_rows_to_insert">
  mysql\_max\_rows\_to\_insert
</h2>

<SettingsInfoBlock type="UInt64" default_value="65536" />

The maximum number of rows in MySQL batch insertion of the MySQL storage engine