cast_* session settings

These settings are available in system.settings and are autogenerated from the ClickHouse snapshot.

cast_ipv4_ipv6_default_on_conversion_error

CAST operator into IPv4, CAST operator into IPV6 type, toIPv4, toIPv6 functions will return default value instead of throwing exception on conversion error.

cast_keep_nullable

Enables or disables keeping of the Nullable data type in CAST operations.

When the setting is enabled and the argument of CAST function is Nullable, the result is also transformed to Nullable type. When the setting is disabled, the result always has the destination type exactly.

Possible values:

• 0 — The CAST result has exactly the destination type specified.
• 1 — If the argument type is Nullable, the CAST result is transformed to Nullable(DestinationDataType).

Examples

The following query results in the destination data type exactly:

SET cast_keep_nullable = 0;
SELECT CAST(toNullable(toInt32(0)) AS Int32) as x, toTypeName(x);

Result:

┌─x─┬─toTypeName(CAST(toNullable(toInt32(0)), 'Int32'))─┐
│ 0 │ Int32                                             │
└───┴───────────────────────────────────────────────────┘

The following query results in the Nullable modification on the destination data type:

SET cast_keep_nullable = 1;
SELECT CAST(toNullable(toInt32(0)) AS Int32) as x, toTypeName(x);

Result:

┌─x─┬─toTypeName(CAST(toNullable(toInt32(0)), 'Int32'))─┐
│ 0 │ Nullable(Int32)                                   │
└───┴───────────────────────────────────────────────────┘

See Also

• CAST function